diff --git a/src/api/greptime/v1/admin.proto b/src/api/greptime/v1/admin.proto
index bdf87466f9..842e885c72 100644
--- a/src/api/greptime/v1/admin.proto
+++ b/src/api/greptime/v1/admin.proto
@@ -18,6 +18,7 @@ message AdminExpr {
   ExprHeader header = 1;
   oneof expr {
     CreateExpr create = 2;
+    AlterExpr alter = 3;
   }
 }
 
@@ -39,3 +40,16 @@ message CreateExpr {
   bool create_if_not_exists = 8;
   map<string, string> table_options = 9;
 }
+
+message AlterExpr {
+  optional string catalog_name = 1;
+  optional string schema_name = 2;
+  string table_name = 3;
+  oneof kind {
+    AddColumn add_column = 4;
+  }
+}
+
+message AddColumn {
+  ColumnDef column_def = 1;
+}