Firstly, the basic principle of the quantitative pump load sensing system is described. The circuit is composed of two load cases, and the function of each component in the circuit is analyzed. Then taken the bypass pressure compensation valve flow control loop as the study object, the flow control valve of the simplified physical model was drawn, the two series dynamic mathematical model of damping hole and flow control valve were established, through the MATLAB, the damping characteristics of series damping hole and structure parameters of influence on control oil pressure change were analyzed, and the effect of damping hole length and diameter on oil pressure was compared. Finally damping hole to prevent oil pressure oscillation characteristics is simulated with analysis, providing the theoretical design basis for control parameters of orifice.