Abstract: Stress state of pulsation water-hammer with high pressure（new coal water-injection equipment） was analyzed based on its influence of structure parameter on its function by simulation method.Mathematic model of this equipment was set up by differential equation.Simulation model was built up with Matlab/Simulink dynamic simulation tools.Simulation result was proved be feasible by comparing it with experimental result.Influence of main spring rigidity on output pressure and opening of main valve core was analyzed.Results showed that rigidity of main spring reduced from 2250Kn/m to 1000Kn/m,summit pressure of the equipment increased and stable pressure increased also,opening of main valve core were 10mm.