The inlet deflection angle is an important blade design parameter with respect to both performance and manufacturability of torque converters. This study investigated the influence of the inlet deflection angle on the performance of torque converters and a method of optimizing the inlet deflection angle for torque converters based on 3D flow simulation is presented. Parameter analysis and multi-objective optimization were performed on an automated 3D flow simulation platform. The results indicate that the mass flow rate increases with a decreasing difference between the pump outlet deflection angle and the turbine inlet deflection angle, consequently increasing pump capacity factor. The advantages of the method proposed are an improved design quality and a significantly shorter design cycle.