diff --git a/backend/src/Health.WebApi/Middleware/exception_middleware.cs b/backend/src/Health.WebApi/Middleware/exception_middleware.cs
index c7254bc..bcc41d1 100644
--- a/backend/src/Health.WebApi/Middleware/exception_middleware.cs
+++ b/backend/src/Health.WebApi/Middleware/exception_middleware.cs
@@ -24,6 +24,15 @@ public sealed class ExceptionMiddleware(RequestDelegate next, ILogger<ExceptionM
             var result = new { code = 40001, data = (object?)null, message = vex.Message };
             await context.Response.WriteAsync(JsonSerializer.Serialize(result));
         }
+        catch (Microsoft.AspNetCore.Http.BadHttpRequestException ex)
+        {
+            // 请求体无法解析（非法 JSON、编码错误、请求体过大等）：返回其携带的状态码（通常 400），而不是 500
+            _logger.LogWarning(ex, "请求解析失败: {Path}", context.Request.Path);
+            context.Response.StatusCode = ex.StatusCode;
+            context.Response.ContentType = "application/json";
+            var result = new { code = 40001, data = (object?)null, message = "请求格式不正确" };
+            await context.Response.WriteAsync(JsonSerializer.Serialize(result));
+        }
         catch (Exception ex)
         {
             // 生产环境不暴露内部异常详情