In order to find out the cause of influence on efficiency of the torque converter and provide theoretical direction to improve performance and design and manufacture level of the converter, by using Fluent, the three-dimensional internal flow field of the converter was numerically simulated by using segregated solver, absolute velocity formulation, standard k-ε model, standard wall functions, second order upwind discretization, SIMPLE pressure-velocity coupling, pressure inlet and outlet, and mixing-plane model. By numerical calculation, the whole flow distribution in the different work conditions was attained and the performance characteristics curves of the converter were also gained. Finally calculated results were compared with the experimental results and maximum error was less than 5% percent, which proved that three-dimensional calculation was correct