diff --git a/backend/internal/handler/admin/dashboard_handler.go b/backend/internal/handler/admin/dashboard_handler.go
index fe54d75f..30cdd914 100644
--- a/backend/internal/handler/admin/dashboard_handler.go
+++ b/backend/internal/handler/admin/dashboard_handler.go
@@ -26,31 +26,33 @@ func NewDashboardHandler(dashboardService *service.DashboardService) *DashboardH
 }
 
 // parseTimeRange parses start_date, end_date query parameters
+// Uses user's timezone if provided, otherwise falls back to server timezone
 func parseTimeRange(c *gin.Context) (time.Time, time.Time) {
-	now := timezone.Now()
+	userTZ := c.Query("timezone") // Get user's timezone from request
+	now := timezone.NowInUserLocation(userTZ)
 	startDate := c.Query("start_date")
 	endDate := c.Query("end_date")
 
 	var startTime, endTime time.Time
 
 	if startDate != "" {
-		if t, err := timezone.ParseInLocation("2006-01-02", startDate); err == nil {
+		if t, err := timezone.ParseInUserLocation("2006-01-02", startDate, userTZ); err == nil {
 			startTime = t
 		} else {
-			startTime = timezone.StartOfDay(now.AddDate(0, 0, -7))
+			startTime = timezone.StartOfDayInUserLocation(now.AddDate(0, 0, -7), userTZ)
 		}
 	} else {
-		startTime = timezone.StartOfDay(now.AddDate(0, 0, -7))
+		startTime = timezone.StartOfDayInUserLocation(now.AddDate(0, 0, -7), userTZ)
 	}
 
 	if endDate != "" {
-		if t, err := timezone.ParseInLocation("2006-01-02", endDate); err == nil {
+		if t, err := timezone.ParseInUserLocation("2006-01-02", endDate, userTZ); err == nil {
 			endTime = t.Add(24 * time.Hour) // Include the end date
 		} else {
-			endTime = timezone.StartOfDay(now.AddDate(0, 0, 1))
+			endTime = timezone.StartOfDayInUserLocation(now.AddDate(0, 0, 1), userTZ)
 		}
 	} else {
-		endTime = timezone.StartOfDay(now.AddDate(0, 0, 1))
+		endTime = timezone.StartOfDayInUserLocation(now.AddDate(0, 0, 1), userTZ)
 	}
 
 	return startTime, endTime
diff --git a/backend/internal/handler/admin/usage_handler.go b/backend/internal/handler/admin/usage_handler.go
index 37da93d3..9d14afd2 100644
--- a/backend/internal/handler/admin/usage_handler.go
+++ b/backend/internal/handler/admin/usage_handler.go
@@ -102,8 +102,9 @@ func (h *UsageHandler) List(c *gin.Context) {
 
 	// Parse date range
 	var startTime, endTime *time.Time
+	userTZ := c.Query("timezone") // Get user's timezone from request
 	if startDateStr := c.Query("start_date"); startDateStr != "" {
-		t, err := timezone.ParseInLocation("2006-01-02", startDateStr)
+		t, err := timezone.ParseInUserLocation("2006-01-02", startDateStr, userTZ)
 		if err != nil {
 			response.BadRequest(c, "Invalid start_date format, use YYYY-MM-DD")
 			return
@@ -112,7 +113,7 @@ func (h *UsageHandler) List(c *gin.Context) {
 	}
 
 	if endDateStr := c.Query("end_date"); endDateStr != "" {
-		t, err := timezone.ParseInLocation("2006-01-02", endDateStr)
+		t, err := timezone.ParseInUserLocation("2006-01-02", endDateStr, userTZ)
 		if err != nil {
 			response.BadRequest(c, "Invalid end_date format, use YYYY-MM-DD")
 			return
@@ -172,7 +173,8 @@ func (h *UsageHandler) Stats(c *gin.Context) {
 	}
 
 	// Parse date range
-	now := timezone.Now()
+	userTZ := c.Query("timezone") // Get user's timezone from request
+	now := timezone.NowInUserLocation(userTZ)
 	var startTime, endTime time.Time
 
 	startDateStr := c.Query("start_date")
@@ -180,12 +182,12 @@ func (h *UsageHandler) Stats(c *gin.Context) {
 
 	if startDateStr != "" && endDateStr != "" {
 		var err error
-		startTime, err = timezone.ParseInLocation("2006-01-02", startDateStr)
+		startTime, err = timezone.ParseInUserLocation("2006-01-02", startDateStr, userTZ)
 		if err != nil {
 			response.BadRequest(c, "Invalid start_date format, use YYYY-MM-DD")
 			return
 		}
-		endTime, err = timezone.ParseInLocation("2006-01-02", endDateStr)
+		endTime, err = timezone.ParseInUserLocation("2006-01-02", endDateStr, userTZ)
 		if err != nil {
 			response.BadRequest(c, "Invalid end_date format, use YYYY-MM-DD")
 			return
@@ -195,13 +197,13 @@ func (h *UsageHandler) Stats(c *gin.Context) {
 		period := c.DefaultQuery("period", "today")
 		switch period {
 		case "today":
-			startTime = timezone.StartOfDay(now)
+			startTime = timezone.StartOfDayInUserLocation(now, userTZ)
 		case "week":
 			startTime = now.AddDate(0, 0, -7)
 		case "month":
 			startTime = now.AddDate(0, -1, 0)
 		default:
-			startTime = timezone.StartOfDay(now)
+			startTime = timezone.StartOfDayInUserLocation(now, userTZ)
 		}
 		endTime = now
 	}
diff --git a/backend/internal/handler/usage_handler.go b/backend/internal/handler/usage_handler.go
index 9e503d4c..129dbfa6 100644
--- a/backend/internal/handler/usage_handler.go
+++ b/backend/internal/handler/usage_handler.go
@@ -88,8 +88,9 @@ func (h *UsageHandler) List(c *gin.Context) {
 
 	// Parse date range
 	var startTime, endTime *time.Time
+	userTZ := c.Query("timezone") // Get user's timezone from request
 	if startDateStr := c.Query("start_date"); startDateStr != "" {
-		t, err := timezone.ParseInLocation("2006-01-02", startDateStr)
+		t, err := timezone.ParseInUserLocation("2006-01-02", startDateStr, userTZ)
 		if err != nil {
 			response.BadRequest(c, "Invalid start_date format, use YYYY-MM-DD")
 			return
@@ -98,7 +99,7 @@ func (h *UsageHandler) List(c *gin.Context) {
 	}
 
 	if endDateStr := c.Query("end_date"); endDateStr != "" {
-		t, err := timezone.ParseInLocation("2006-01-02", endDateStr)
+		t, err := timezone.ParseInUserLocation("2006-01-02", endDateStr, userTZ)
 		if err != nil {
 			response.BadRequest(c, "Invalid end_date format, use YYYY-MM-DD")
 			return
@@ -194,7 +195,8 @@ func (h *UsageHandler) Stats(c *gin.Context) {
 	}
 
 	// 获取时间范围参数
-	now := timezone.Now()
+	userTZ := c.Query("timezone") // Get user's timezone from request
+	now := timezone.NowInUserLocation(userTZ)
 	var startTime, endTime time.Time
 
 	// 优先使用 start_date 和 end_date 参数
@@ -204,12 +206,12 @@ func (h *UsageHandler) Stats(c *gin.Context) {
 	if startDateStr != "" && endDateStr != "" {
 		// 使用自定义日期范围
 		var err error
-		startTime, err = timezone.ParseInLocation("2006-01-02", startDateStr)
+		startTime, err = timezone.ParseInUserLocation("2006-01-02", startDateStr, userTZ)
 		if err != nil {
 			response.BadRequest(c, "Invalid start_date format, use YYYY-MM-DD")
 			return
 		}
-		endTime, err = timezone.ParseInLocation("2006-01-02", endDateStr)
+		endTime, err = timezone.ParseInUserLocation("2006-01-02", endDateStr, userTZ)
 		if err != nil {
 			response.BadRequest(c, "Invalid end_date format, use YYYY-MM-DD")
 			return
@@ -221,13 +223,13 @@ func (h *UsageHandler) Stats(c *gin.Context) {
 		period := c.DefaultQuery("period", "today")
 		switch period {
 		case "today":
-			startTime = timezone.StartOfDay(now)
+			startTime = timezone.StartOfDayInUserLocation(now, userTZ)
 		case "week":
 			startTime = now.AddDate(0, 0, -7)
 		case "month":
 			startTime = now.AddDate(0, -1, 0)
 		default:
-			startTime = timezone.StartOfDay(now)
+			startTime = timezone.StartOfDayInUserLocation(now, userTZ)
 		}
 		endTime = now
 	}
@@ -248,31 +250,33 @@ func (h *UsageHandler) Stats(c *gin.Context) {
 }
 
 // parseUserTimeRange parses start_date, end_date query parameters for user dashboard
+// Uses user's timezone if provided, otherwise falls back to server timezone
 func parseUserTimeRange(c *gin.Context) (time.Time, time.Time) {
-	now := timezone.Now()
+	userTZ := c.Query("timezone") // Get user's timezone from request
+	now := timezone.NowInUserLocation(userTZ)
 	startDate := c.Query("start_date")
 	endDate := c.Query("end_date")
 
 	var startTime, endTime time.Time
 
 	if startDate != "" {
-		if t, err := timezone.ParseInLocation("2006-01-02", startDate); err == nil {
+		if t, err := timezone.ParseInUserLocation("2006-01-02", startDate, userTZ); err == nil {
 			startTime = t
 		} else {
-			startTime = timezone.StartOfDay(now.AddDate(0, 0, -7))
+			startTime = timezone.StartOfDayInUserLocation(now.AddDate(0, 0, -7), userTZ)
 		}
 	} else {
-		startTime = timezone.StartOfDay(now.AddDate(0, 0, -7))
+		startTime = timezone.StartOfDayInUserLocation(now.AddDate(0, 0, -7), userTZ)
 	}
 
 	if endDate != "" {
-		if t, err := timezone.ParseInLocation("2006-01-02", endDate); err == nil {
+		if t, err := timezone.ParseInUserLocation("2006-01-02", endDate, userTZ); err == nil {
 			endTime = t.Add(24 * time.Hour) // Include the end date
 		} else {
-			endTime = timezone.StartOfDay(now.AddDate(0, 0, 1))
+			endTime = timezone.StartOfDayInUserLocation(now.AddDate(0, 0, 1), userTZ)
 		}
 	} else {
-		endTime = timezone.StartOfDay(now.AddDate(0, 0, 1))
+		endTime = timezone.StartOfDayInUserLocation(now.AddDate(0, 0, 1), userTZ)
 	}
 
 	return startTime, endTime
diff --git a/backend/internal/pkg/timezone/timezone.go b/backend/internal/pkg/timezone/timezone.go
index 35795648..40f6e38f 100644
--- a/backend/internal/pkg/timezone/timezone.go
+++ b/backend/internal/pkg/timezone/timezone.go
@@ -122,3 +122,40 @@ func StartOfMonth(t time.Time) time.Time {
 func ParseInLocation(layout, value string) (time.Time, error) {
 	return time.ParseInLocation(layout, value, Location())
 }
+
+// ParseInUserLocation parses a time string in the user's timezone.
+// If userTZ is empty or invalid, falls back to the configured server timezone.
+func ParseInUserLocation(layout, value, userTZ string) (time.Time, error) {
+	loc := Location() // default to server timezone
+	if userTZ != "" {
+		if userLoc, err := time.LoadLocation(userTZ); err == nil {
+			loc = userLoc
+		}
+	}
+	return time.ParseInLocation(layout, value, loc)
+}
+
+// NowInUserLocation returns the current time in the user's timezone.
+// If userTZ is empty or invalid, falls back to the configured server timezone.
+func NowInUserLocation(userTZ string) time.Time {
+	if userTZ == "" {
+		return Now()
+	}
+	if userLoc, err := time.LoadLocation(userTZ); err == nil {
+		return time.Now().In(userLoc)
+	}
+	return Now()
+}
+
+// StartOfDayInUserLocation returns the start of the given day in the user's timezone.
+// If userTZ is empty or invalid, falls back to the configured server timezone.
+func StartOfDayInUserLocation(t time.Time, userTZ string) time.Time {
+	loc := Location()
+	if userTZ != "" {
+		if userLoc, err := time.LoadLocation(userTZ); err == nil {
+			loc = userLoc
+		}
+	}
+	t = t.In(loc)
+	return time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, loc)
+}
diff --git a/frontend/src/api/client.ts b/frontend/src/api/client.ts
index 1cc8e55b..4e53069a 100644
--- a/frontend/src/api/client.ts
+++ b/frontend/src/api/client.ts
@@ -21,6 +21,15 @@ export const apiClient: AxiosInstance = axios.create({
 
 // ==================== Request Interceptor ====================
 
+// Get user's timezone
+const getUserTimezone = (): string => {
+  try {
+    return Intl.DateTimeFormat().resolvedOptions().timeZone
+  } catch {
+    return 'UTC'
+  }
+}
+
 apiClient.interceptors.request.use(
   (config: InternalAxiosRequestConfig) => {
     // Attach token from localStorage
@@ -34,6 +43,14 @@ apiClient.interceptors.request.use(
       config.headers['Accept-Language'] = getLocale()
     }
 
+    // Attach timezone for all GET requests (backend may use it for default date ranges)
+    if (config.method === 'get') {
+      if (!config.params) {
+        config.params = {}
+      }
+      config.params.timezone = getUserTimezone()
+    }
+
     return config
   },
   (error) => {