In this paper, a quasi-three-dimensional design method of torque converter blade is presented, and a turbine example is designed. In addition, a new way that three-dimensional flow field calculation is added into traditional blade design is given and the judge rule of flow field is presented. The blade system of a Chinese made YB 300 torque converter has been redesigned with the aid of the new way, and its performance has been improved. The experiment shows that the maximum efficiency has been raised from original 84. 7% to 86%, with other factors such as stall torque ratio and so on unchanged or a little better.