As a result of pressure oil action, the force imbalance makes the rotor torque. The output torque of a vane hydraulic motor is related to the displacement of the hydraulic motor and the pressure difference between the inlet and outlet of the hydraulic motor. Since hydraulic motors are generally required to be positive and negative, the blades of the vane type hydraulic motors should be placed in the radial direction. In order to make the blade root pressure on oil, pressure oil cavity ordinary check valve should be set up on the path of blade root. In order to ensure the vane hydraulic motor that can normal boot after pressure oil factory, it must make the top and the stator blade surface close contact to ensure a good seal. Therefore, the preloaded spring should be set up at the blade root. Vane type hydraulic motor is small in volume, small in rotation inertia, sensitive in action and suitable for high frequency of commutation. However, the leakage is large and the operation is unstable at low speed. Therefore, vane hydraulic motor is generally used for high speed, low torque and sensitive operation.