Abstract: The influence on torque of three viscosities, three original filling rates and three rotational speed differences were discussed in order to study the torque characteristics of liquid viscous coupling. It was showed that the higher of the viscosity, the lower of the minimum speed difference. When the filling rate is less than 90%, no hump was founded. Moreover, input speed has no influence on hump. The surface temperature of liquid viscous coupling was also given, which is important for researching the temperature changing in liquid viscous coupling.