Axial piston pumps can be divided into Swash Plate Type and Bent-axial Type. The pump consists of swash plate, plunger, cylinder, oil distribution plate and other major components, swash plate and oil distribution plate is immobile, the drive shaft drives the cylinder, plunger rotation, plunger by mechanical devices or in the low-pressure oil pressure on the swash plate. When the drive shaft rotates, the plunger gradually extends to the outside of the cylinder body during the half week of the bottom-up rotation along the swash plate, so that the volume of the sealing chamber in the cylinder body hole increases continuously, generating a local vacuum, so that the oil will be sucked in through the oil dispensing window on the oil dispensing plate: the plunger gradually pushes in during the half-week of the rotation along the top and bottom of the swash plate, so that the volume of the sealing chamber decreases continuously, and the oil will be discharged outward from the oil dispensing window of the oil dispensing plate, and the cylinder body will not be moved. Every turn, each plunger reciprocating movement once, complete a suction action. Changing the inclination angle of the swash plate, you can change the effective change of the sealing working volume, to realize the pump variable.