diff --git a/backend/internal/pkg/antigravity/request_transformer.go b/backend/internal/pkg/antigravity/request_transformer.go
index 1b21bd58..80063cb8 100644
--- a/backend/internal/pkg/antigravity/request_transformer.go
+++ b/backend/internal/pkg/antigravity/request_transformer.go
@@ -490,9 +490,23 @@ func parseToolResultContent(content json.RawMessage, isError bool) string {
 }
 
 // buildGenerationConfig 构建 generationConfig
+const (
+	defaultMaxOutputTokens   = 64000
+	maxOutputTokensUpperBound = 65000
+	maxOutputTokensClaude     = 64000
+)
+
+func maxOutputTokensLimit(model string) int {
+	if strings.HasPrefix(model, "claude-") {
+		return maxOutputTokensClaude
+	}
+	return maxOutputTokensUpperBound
+}
+
 func buildGenerationConfig(req *ClaudeRequest) *GeminiGenerationConfig {
+	maxLimit := maxOutputTokensLimit(req.Model)
 	config := &GeminiGenerationConfig{
-		MaxOutputTokens: 64000, // 默认最大输出
+		MaxOutputTokens: defaultMaxOutputTokens, // 默认最大输出
 		StopSequences:   DefaultStopSequences,
 	}
 
@@ -516,6 +530,10 @@ func buildGenerationConfig(req *ClaudeRequest) *GeminiGenerationConfig {
 		}
 	}
 
+	if config.MaxOutputTokens > maxLimit {
+		config.MaxOutputTokens = maxLimit
+	}
+
 	// 其他参数
 	if req.Temperature != nil {
 		config.Temperature = req.Temperature