diff --git a/api/api.proto b/api/api.proto
index 77e4be1938c..3b3f8a038ef 100644
--- a/api/api.proto
+++ b/api/api.proto
@@ -38,6 +38,10 @@ service Wallet {
 
   rpc ListWitnesses (EmptyMessage) returns (WitnessList) {
 
+  };
+  
+  rpc UpdateWitness (WitnessUpdateContract) returns (Transaction) {
+
   };
 
   rpc CreateWitness (WitnessCreateContract) returns (Transaction) {
diff --git a/core/Contract.proto b/core/Contract.proto
index 8b3fff1167f..105f28a47d9 100644
--- a/core/Contract.proto
+++ b/core/Contract.proto
@@ -61,7 +61,12 @@ message VoteWitnessContract {
 
 message WitnessCreateContract {
   bytes owner_address = 1;
-  bytes url = 12;
+  bytes url = 2;
+}
+
+message WitnessUpdateContract {
+  bytes owner_address = 1;
+  bytes update_url = 12;
 }
 
 message AssetIssueContract {
diff --git a/core/Tron.proto b/core/Tron.proto
index fc48f122c51..75b0e80882b 100644
--- a/core/Tron.proto
+++ b/core/Tron.proto
@@ -79,6 +79,7 @@ message Transaction {
       WitnessCreateContract = 5;
       AssetIssueContract = 6;
       DeployContract = 7;
+      WitnessUpdateContract = 8;
     }
     ContractType type = 1;
     google.protobuf.Any parameter = 2;