Abstract:The friction stir welding (FSW) was carried out on 6061-T6 aluminum alloy plate with 3.88mm thickness, and 20Hz ultrasonic assisted welding (UAFSW) was added in half of welding. The microstructures and mechanical properties of UAFSW and FSW welds were compared and analyzed. It was found that the surface texture of the weld was smoother and more dense, the organization of grain is more small, and The corrosion resistance is deteriorated causing the macrostructure color of the microstructure Dim,SEM second phase of the overall row has a certain direction.The microhardness is greater than the trough at the peak. The minimum value of 65.8HV is 52.2% in the base metal zone, while the distance from the weld center is greater than FSW at the same distance UAFSW.