Abstract: As a key component of the torque converter, one-way clutch can switch the modes between torque converter and coupling conditions, playing a crucial role in the transmission performance and reliable operation of the integrated torque converter. To investigate the torque performance and flow characteristics of the one-way clutch, combining the CFD numerical analysis, experiments and tests, an effective method was arranged to study the resistance torque and flow field characteristics of the one-way clutch for torque converters. In this study, the flow field distribution characteristics and oil stirring torque variations of the one-way clutch were analyzed under different ambient temperatures, establishing a mapping relationship among the external ring oil stirring torque, rotational speed, and ambient temperature. The results show that the oil stirring torque of the one-way clutch is related to the pressure, flow velocity and vorticity of the internal oil, and the values of flow field parameters are increasing generally with the temperature decreasing, representing especially evidence near the external ring profile. When the external ring speed is between 800~2200 r/min, the external ring oil stirring torque is usually in the range from 6 to 26 N·m. Additionally, at an external ring speed of 2000 r/min, the maximum pressure on its profile can reach 200 kPa, and the surface fluid flow velocity can reach 20 m/s.