Abstract: Water hammer pressure of throttle valve is presentedbased on the invalidation of throttle slice in hydro-pneumatic spring duringthe field tests. The physical model of throttle valve with annular slice isbuilt. The water hammer calculation of damping valve is performed by usingthe water hammer theory and the solving method of latent line for thepartial differential equations. The invalidation reasons of throttle sliceare analyzed through numerical simulation. The influences of throttleorifice structure on water hammer and damping force of throttle valve arealso researched. The method of valve reliability is evaluated from yield andfatigue and the calculation example is carried out. The obtained results canprovide reference for the throttle valve reliability in order to avoid thebreak of the throttle slice.