diff --git a/src/app/OlMap/Controls/Timeline.tsx b/src/app/OlMap/Controls/Timeline.tsx
index 305cf3a..32080a8 100644
--- a/src/app/OlMap/Controls/Timeline.tsx
+++ b/src/app/OlMap/Controls/Timeline.tsx
@@ -314,7 +314,7 @@ const Timeline: React.FC<TimelineProps> = ({
       if (timeRange) {
         if (next < minTime) next = maxTime;
       } else {
-        if (next <= 0) next = 1440;
+        if (next < 0) next += 1440;
       }
       return next;
     });
diff --git a/src/components/olmap/HealthRiskAnalysis/Timeline.tsx b/src/components/olmap/HealthRiskAnalysis/Timeline.tsx
index 1dd727d..9c5a401 100644
--- a/src/components/olmap/HealthRiskAnalysis/Timeline.tsx
+++ b/src/components/olmap/HealthRiskAnalysis/Timeline.tsx
@@ -177,7 +177,7 @@ const Timeline: React.FC<TimelineProps> = ({
   const handleStepBackward = useCallback(() => {
     setCurrentYear((prev: number) => {
       let next = prev - 1;
-      if (next < minTime) next = maxTime;
+      if (next < minTime) next += maxTime - minTime + 1;
       return next;
     });
   }, [minTime, maxTime]);