Axial plunger pump can be used as hydraulic motor in principle except valve type distribution. That is to say, axial piston pump and axial piston motor are reversible. The working principle of the axial plunger motor is that the oil distribution plate and the inclined plate are fixed and the motor shaft is connected with the cylinder body. When the pressure oil enters the cylinder's plunger hole through the window of the oil distribution plate, the plunger extends out under the action of pressure oil, and a normal reaction p is generated against the plunger by the inclined disk, which can be decomposed into axial force and vertical force Q. The liquid pressure on the plunger is balanced by Q, which causes the plunger to produce a torque to the center of the cylinder, driving the motor shaft to rotate counterclockwise. The instantaneous total torque produced by the axial plunger motor is pulsating. If the motor pressure oil input direction changes, the motor shaft rotation clockwise direction. The change of inclined Angle a of inclined disk. That is to say, the change of displacement not only affects the torque of the motor, but also affects its speed and steering. The larger the inclined Angle of inclined disk. The larger the torque, the lower the rotational speed.