Abstract: The surface layer of the welded joint of 7A52 aluminum alloy was treated by high-energy shot peening(HESP) technique,the microstructure,grain size,deformation layer thickness,microhardness and wear resistance were analyzed after surface nanocrystallization.The results showed that after 20 min high-energy shot peening,the surface of the average grain sizes of the base material,welded and heat affected zone were 28.2 nm,24.7 nm and 34.4 nm,deformed layer thickness of surface was about 36.5 μm,after the high-energy shot peening,surface hardness were improved,the wear rate of welded joint was 0.005 6% after surface nanocrystallization,which was 29.9% wear rate of welded joint before surface nanocrystallization.