Abstract: For studying the internal flow field and dynamic characteristics of pressure-regulating valve,its 3-D model is established.Adopting dynamic mesh and subroutine were calculated the internal flow field and movement of the pintle and the result was tested by cold gas experiment.The characteristics of unsteady flow field and shock wave was analysed.Dynamic characteristics of the pintle in some different instances were analysed.The flow field periodically changes because of the vibration of pintle.High inlet-pressure or low pring coefficient can make the flow field to have vehemently motorial pintle steady faster but higher peak value in some quantities,such as the flow rate or displacement of the pintle.