In order to reduce the impact of flow distribution,the piston cavity of high-pressure piston pump must realize pre-pressure rise and pre-pressure release through the joint action of mechanical closed compression,expansion and oil introduction of damping groove in the transition process.In this process,the two ends of the damping groove are acted on a large varying differential pressure,and the oil in the groove produces a high-speed differential pressure flow,the low-pressure areas are generated,the cavitation is formed,and the cavitation is occured when the bubble is broken,the surfaces of the valve plate and cylinder block are destroyed,and the volume efficiency of the pump is greatly reduced.The durability test was conducted,the characteristics of distribution cavitation damage and the change of volumetric efficiency were studied.The results show that under the existing distribution structure,the distribution cavitation is serious,durability test only carries out 600 h,the surface of the cylinder has appeares serious gas erosion damage,the pump volume efficiency droppes significantly.To improve the pump durability and volume efficiency,gas corrosion resistance structure must be studied to reduce the current gas erosion damage of the current subsurface.