Torque converter W305 equipped in off-road vehicle was modeled and the internal flow field was calculated by using the program CFD. For disposing the interaction between the three impellers with different speeds, the theory of the mixing plane was used in the calculation. Based on the numerical results, the distribution of the velocity and pressure of the internal flow especially in the stator were analyzed. The experimental data of the flow field of stator were compared with the numerical results, and it was proved that the calculated results showed agreement with the experiment accurately.