In order to reduce waterhammer and noise in absorbing and discharging process of the highpressure piston pump, the preloading process and preunloading process are realized through the combined action of mechanical closure compression, expansion and the fluid guided in the silencing grooves in transition regions of absorbing process and discharging process. In this process, the emergence of the lowpressure area and forming air cavitation are generated by a large differential change pressure in the silencing grooves and a large differential pressure fluctuation at a high speed in the oil of the silencing grooves, and when the bubbles break up again, occurance of cavitation erosion damages the valve plate and cylinder surface.It is an effective method to control cavitation damage of highpressure piston pump by optimizing the parameters and structure of the silencing grooves, reducing the volume content of cavitation, changing the location of cavitation and making the bubble break away from the valve plate and the surface of cylinder.