To investigate the effects of pressure side winglet on aerodynamic performance of high subsonic compressor cascade at different Inlet Mach Number, the experimental study has been carried out to explore the original cascade and cascades with different pressure side winglets at different Inlet Mach Number(Ma=0.5,Ma=0.6 and Ma=0.7). The results show that the pressure side winglet not only weakens the pressure gradient on both sides of the blade, but also obstructs flow into the tip clearance. At the same time the pressure side winglet can inhibit the tip leakage flow and reduce the flow loss under the condition of high subsonic, thus the tip clearance flow is improved. With the increase of pressure side winglet width, the improvement degree is increased, and the change of Mach number is proportional to the control effect. The most effective pressure side winglet is PW2.0 at inlet Mach number of 0.7, which provides the most significant aerodynamic loss reduction by 6.53% compared to the original cascade at the same inlet Mach number .