A certain type piston pump with prepressure boost groove and precompression chamber was taken as the object, and the digital modeling and simulation were carried out.Aimed at the mechanical and hydraulic coupling problem of piston pump, considering the compressibility of the fluid,a digital model of the whole piston pump was established by using the AMESim software.The relative throttle area value was introduced into the piston flow sub model and piston flow distribution sub model respectively, which was controlled by using the piecewise function,thus the digitization of the leakage of the piston pair, flow distribution pair, slipper pair and flow distribution for the groove cavity combined structure were realized.Through the simulation of the whole piston pump, the influence of the cavity structure parameter on the performance of the plunger pump was analyzed.The experimental platform of the plunger pump was built, the correctness of the digital model was verified. It provides a theoretical basis for the structural optimization of the pump