Abstract: For multi layer and multi pass welding technology of V-type groove in medium and heavy plate,the robot welding was studied,and a new welding method of multi-layer multi-pass robot welding was designed with the deviation instruction in robot program. By planning the welding sequence and the welding path of the robot,the offset of each target point was calculated by using the simplified welding section,and the programming of the robot was completed. The proposed method was tested and validated by the robot off-line programming software Robot Studio and the actual welding equipment. The results show that the method can effectively reduce the frequency of teaching,improve the welding efficiency,the filling effect of the V-groove plate after welding and the weld appearance are good.