diff --git a/relay/channel/claude/relay-claude.go b/relay/channel/claude/relay-claude.go
index 21427b1f..2982945c 100644
--- a/relay/channel/claude/relay-claude.go
+++ b/relay/channel/claude/relay-claude.go
@@ -811,7 +811,8 @@ func HandleStreamFinalResponse(c *gin.Context, info *relaycommon.RelayInfo, clau
 		}
 		// 只补缺失字段，不整份覆盖——保留 message_start 已拿到的 cache 字段
 		fallback := service.ResponseText2Usage(c, claudeInfo.ResponseText.String(), info.UpstreamModelName, info.GetEstimatePromptTokens())
-		if claudeInfo.Usage.CompletionTokens == 0 {
+		if claudeInfo.Usage.CompletionTokens == 0 ||
+			(!claudeInfo.Done && fallback.CompletionTokens > claudeInfo.Usage.CompletionTokens) {
 			claudeInfo.Usage.CompletionTokens = fallback.CompletionTokens
 		}
 		if claudeInfo.Usage.PromptTokens == 0 {