The surface roughness and surface integrity resulting from net-shape processing may be detrimental to the fatigue-life and cerrosion resistance of engineering components.The most common methods enrolled for fatigue-life improvement include shot peening,roller bumishing and abrasive finishing.Laser peening and waterjet peening have also recently emerged as viable alternatives to conventional methods of surface treatment.As a new surface strengthening method,high pressure waterjet peening (WJP) is used to improve fatigue life by introducing near-surface compressive residual stresses.In this paper,the submerged waterjet was adopted to strengthen the specimen surfaces of 7075-T651 aluminum alloy.The effects of WJPs parameters on the microstructure and surface properties of as-treated samples were researched.