Swashplate axial piston pumps generally exist in the form of cylindrical rotation and end-face distribution. The end face of the cylinder block is inlaid with friction pairs composed of bimetallic plates and steel plates, most of which adopt the method of planar flow distribution, which is more convenient for maintenance. The oil pan is one of the key components of the axial piston pump. When the pump, on the one hand, the high-pressure oil working chamber of the cylinder facing the oil pan is formed between the oil pan and the cylinder block in the oil film pressure distribution on the other hand. The valve plate is away from the hydraulic cylinder of the thrust reverser of the cylinder. The design hydraulic pressing force Fn of the cylinder block to the oil distribution plate is slightly larger than the hydraulic reverse thrust Ff of the oil distribution plate to the cylinder block, namely Fn/Ff=1.05~1.1 so that the pump works normally and maintains high volumetric efficiency.