diff --git a/bdchain/api/ac_chain.proto b/bdchain/api/ac_chain.proto
index 3d1cea9..af86ddd 100644
--- a/bdchain/api/ac_chain.proto
+++ b/bdchain/api/ac_chain.proto
@@ -11,11 +11,11 @@ option java_multiple_files = true;
 
 service AccountingChain {
     rpc BlockNumber (BlockNumberRequest) returns (BlockNumberResponse);
-    rpc GetBlockByNumber (GetBlockByNumberRequest) returns (Block);
-    rpc GetBlockByHash (GetBlockByHashRequest) returns (Block);
-    rpc GetTransactionByHash (GetTransactionByHashRequest) returns (Transaction);
-    rpc GetTransactionByBlockNumberAndIndex (GetTransactionByBlockNumberAndIndexRequest) returns (Transaction);
-    rpc GetTransactionByBlockHashAndIndex (GetTransactionByBlockHashAndIndexRequest) returns (Transaction);
+    rpc GetBlockByNumber (GetBlockByNumberRequest) returns (BlockResponse);
+    rpc GetBlockByHash (GetBlockByHashRequest) returns (BlockResponse);
+    rpc GetTransactionByHash (GetTransactionByHashRequest) returns (TransactionResponse);
+    rpc GetTransactionByBlockNumberAndIndex (GetTransactionByBlockNumberAndIndexRequest) returns (TransactionResponse);
+    rpc GetTransactionByBlockHashAndIndex (GetTransactionByBlockHashAndIndexRequest) returns (TransactionResponse);
 }
 
 message Transaction {
@@ -49,7 +49,8 @@ message BlockNumberRequest {
     string ledger = 1;
 }
 message BlockNumberResponse {
-    uint64 block_number = 1;
+    Error error = 1;
+    uint64 block_number = 2;
 }
 
 message GetBlockByNumberRequest {
@@ -64,6 +65,11 @@ message GetBlockByHashRequest {
     bool full_transaction = 3;
 }
 
+message BlockResponse {
+    Error error = 1;
+    Block block = 2;
+}
+
 message GetTransactionByHashRequest {
     string ledger = 1;
     bytes hash = 2;
@@ -80,3 +86,8 @@ message GetTransactionByBlockHashAndIndexRequest {
     bytes block_hash = 2;
     uint32 index = 3;
 }
+
+message TransactionResponse {
+    Error error = 1;
+    Transaction transaction = 2;
+}
diff --git a/bdchain/api/common.proto b/bdchain/api/common.proto
index daeb65e..911eef6 100644
--- a/bdchain/api/common.proto
+++ b/bdchain/api/common.proto
@@ -7,6 +7,12 @@ option java_package = "bdchain.api.grpc";
 option java_outer_classname = "CommonProto";
 option java_multiple_files = true;
 
+message Error {
+    string code = 1; // One of a server-defined set of error codes.
+    string message = 2; // A human-readable representation of the error.
+    string target = 3; // The target of the error.
+}
+
 /* 事务类型 */
 enum TransactionType {
     RECORD = 0; // 通用数据记录
diff --git a/bdchain/api/tx_ledger.proto b/bdchain/api/tx_ledger.proto
index d47e7f1..3ddcbe2 100644
--- a/bdchain/api/tx_ledger.proto
+++ b/bdchain/api/tx_ledger.proto
@@ -20,11 +20,12 @@ message CreateLedgerRequest {
     string name = 1;
 }
 message CreateLedgerResponse {
-    bool ok = 1;
+    Error error = 1;
 }
 
 message GetLedgersResponse {
-    repeated string ledgers = 1;
+    Error error = 1;
+    repeated string ledgers = 2;
 }
 
 message SendTransactionRequest {
@@ -38,5 +39,6 @@ message SendTransactionRequest {
     Transaction transaction = 2;
 }
 message SendTransactionResponse {
-    bytes hash = 1;
+    Error error = 1;
+    bytes hash = 2;
 }