Traditional and ultrasonic shot peening are applied on aluminum alloy 7075-T651 respectively. Surface profiles are observed and the mechanical properties are tested. The result indicates that surface roughness of ultrasonic shot peening specimen is 35.5% of the traditional shot peening one, and both these two processes could make the surface hardened to some degree, while the hardening effectiveness of ultrasonic shot peening is a little higher, and the maximum compressive residual stress of ultrasonic shot peening specimen is increased by 31.9% compared to the traditional shot peening one.