diff --git a/lib/services/api_service.dart b/lib/services/api_service.dart
index ebf8bf6..a13ca0a 100644
--- a/lib/services/api_service.dart
+++ b/lib/services/api_service.dart
@@ -54,12 +54,16 @@ class ApiService {
       switch (response.statusCode) {
         case 200:
           return RegistrationResult.ok();
+        case 400:
+          final body = jsonDecode(response.body) as Map<String, dynamic>;
+          final msg = body['message']?.toString() ?? '请求参数错误';
+          return RegistrationResult.error(msg);
         case 409:
           final body = jsonDecode(response.body) as Map<String, dynamic>;
           return RegistrationResult.duplicate(body);
         default:
           final body = jsonDecode(response.body) as Map<String, dynamic>;
-          final msg = body['error'] ?? body['message'] ?? 'Unknown error (${response.statusCode})';
+          final msg = body['message'] ?? body['error'] ?? 'Unknown error (${response.statusCode})';
           return RegistrationResult.error(msg.toString());
       }
     } catch (e) {