diff --git a/backend/app/api/v1/exchange.py b/backend/app/api/v1/exchange.py
index 2393e91..ae8fba7 100644
--- a/backend/app/api/v1/exchange.py
+++ b/backend/app/api/v1/exchange.py
@@ -1,4 +1,4 @@
-from fastapi import APIRouter
+from fastapi import APIRouter, HTTPException
 from app.services.exchange import ExchangeRateService
 from datetime import datetime
 
@@ -14,7 +14,7 @@ async def convert_currency(
 ):
     rate = await service.get_rate(from_currency, to_currency)
     if rate is None:
-        return {"error": f"No rate available for {from_currency} -> {to_currency}"}
+        raise HTTPException(status_code=404, detail=f"汇率不可用: {from_currency} → {to_currency}")
 
     return {
         "from_currency": from_currency.upper(),