This study carried out digital modeling, simulation and verification analysis on the piston pump which is the key hydraulic component of concrete pump truck system. Based on the analysis of its motion law and working principle, it took the swash plate axial piston pump with conical cylinder blocks as the research object, and characterized the kinematic characteristics and flow characteristics of the piston with the method of space geometry and established a variable pump plunger model with AMESim simulation software. Based on the analysis of constant power control, constant pressure compensator control and electro-hydraulic proportional control variable displacement principle of variable pump, etc., this study established a power-pressure-electro-hydraulic proportional compound controlled variable pump AMESim simulation digital model including sub-models such as the pump body piston model, valve plate model, sliding shoe model, variable mechanism model, etc. The outlet flow characteristics, pressure displacement characteristics, current displacement characteristics and transient response characteristics of the plunger pump were studied through the coordinated control of control of the swash plate inclination angle, motor speed, system load and control current. The research results show that the simulation characteristic curve obtained by using the established hydraulic pump digital model is in good agreement with the test results, and the maximum relative errors of the pressure displacement characteristic and current displacement characteristic prediction are 6.31% and 7.73%, respectively. Thus it verifies the accuracy of the model and provides model supports for digital twins and performance optimization upgrades of construction machinery.