Summarize a new type of friction stir welding method based on the stationary shoulder,and can gain no thinning surface after welding,by researching the split mixing tools,the implement of welding process,the microstructure and mechanical properties.Under the condition that the shoulder is stationary,the method can not only obtain the welded joint with excellent mechanical properties,but also achieve the intended purpose of no flashing,good surface finish after welding and no thinning,and may broaden the application field of friction stir welding to the welding of aluminum alloy structural parts with strict surface configuration.