diff --git a/frontend/mobile-app/lib/core/services/contract_signing_service.dart b/frontend/mobile-app/lib/core/services/contract_signing_service.dart
index 5f80fa8d..183b16d1 100644
--- a/frontend/mobile-app/lib/core/services/contract_signing_service.dart
+++ b/frontend/mobile-app/lib/core/services/contract_signing_service.dart
@@ -346,12 +346,15 @@ class ContractSigningService {
       debugPrint('[ContractSigningService] Base64 长度: ${signatureBase64.length}');
 
       final requestData = {
-        'signatureImage': signatureBase64,
-        'ipAddress': ipAddress,
-        'deviceInfo': deviceInfo,
-        'userAgent': userAgent,
-        'latitude': latitude,
-        'longitude': longitude,
+        'signatureBase64': signatureBase64,  // 后端期望的字段名
+        'signatureHash': '',  // TODO: 计算签名哈希
+        'deviceInfo': {
+          'deviceId': deviceInfo ?? 'unknown',
+          'platform': 'android',
+        },
+        'location': latitude != null && longitude != null
+            ? {'latitude': latitude, 'longitude': longitude}
+            : null,
       };
       debugPrint('[ContractSigningService] 请求 URL: /planting/contract-signing/tasks/$orderNo/sign');
 
@@ -406,12 +409,15 @@ class ContractSigningService {
       debugPrint('[ContractSigningService] Base64 长度: ${signatureBase64.length}');
 
       final requestData = {
-        'signatureImage': signatureBase64,
-        'ipAddress': ipAddress,
-        'deviceInfo': deviceInfo,
-        'userAgent': userAgent,
-        'latitude': latitude,
-        'longitude': longitude,
+        'signatureBase64': signatureBase64,  // 后端期望的字段名
+        'signatureHash': '',  // TODO: 计算签名哈希
+        'deviceInfo': {
+          'deviceId': deviceInfo ?? 'unknown',
+          'platform': 'android',
+        },
+        'location': latitude != null && longitude != null
+            ? {'latitude': latitude, 'longitude': longitude}
+            : null,
       };
       debugPrint('[ContractSigningService] 请求 URL: /planting/contract-signing/tasks/$orderNo/late-sign');