Power chuck is an important component for machine tool. In order to solve the existing problem of oil-allocating for rotating hydraulic cylinder of power chuck, a new kind of rotating hydraulic cylinder based on hydraulic slipring is suggested. The deep circular groove oil film face seal technology is applied in the hydraulic slipring for oil transmission. Taking account of the vary of viscosity, the frictional torque of the seal face is simulated in detail. The experiment data prove the preciseness of the theoretical analysis. These theories provide reference for the practical application of the rotating hydraulic cylinder.