Parameterization design method of cascade system of a hydrodynamic torque converter was overviewed, spline fit curve method was selected to construct based on least-parameter principle. With the analysis and comparison of several typical vane profiles, and parameter design method for torque converter was presented combined with widthvariable circulatory circle design method. An instance was realized by UG/OPEN API. Based on all of above researches, parameter design architecture of cascade system in a torque converter was summarized and put forward, and flexible and convenient design model for 3—D optimum design and manufacture was provided. 