The influences of the endwall corner jet (ECJ) with different locations, yaw angles and jet-to-inflow total pressure ratios on the aerodynamic performance of a high-speed compressor cascade are parametrically investigated by numerical simulation. The results show that the ECJ could weaken the boundary layer separation, reduce the loss and increase the pressure rise effectively by inputting momentum to the low energy corner region. The optimal ECJ location for the loss reduction is slightly downstream of the separation line. With the increase of the yaw angle, more loss reduction is obtained in the near endwall region, whereas the loss near the midspan is enhanced due to the enlarged separation along the blade height. A higher jet-to-inflow total pressure ratio could enhance the pressure rise of the cascade, whereas the mixing losses between the jet and the low energy fluid are also strengthened. The benefit of loss reduction degrades when the jet-to-inflow total pressure ratio is higher than 1.1. Moreover, the ECJ could obtain considerable loss reduction for the incidence ranging from-4° to +4°. A maximum loss reduction up to 15.0% is obtained at the incidence of +2° by the ECJ located at 60% chord with a yaw angle of 30°, whereas the jet-to-inflow mass flow ratio is only 0.57%.