Abstract: Two typical liquid-supplement valves in double-tube gas-pressurized hydraulic dampers of car suspension are compared with each other by experiments and finite element simulations.Three-dimensional Fluid-Structure Interaction models of the two liquid-supplement valves are set up with the Finite Element Analysis code ADINA.The working characteristics,transient fluid pressure and velocity distribution of each valve,as well as the kinematical response of the valve disc,are simulated using the ADINA FSI module.The difference between the orifice structures of this two liquid-supplement valves leads to obvious difference in liquid-supplement capacity between them,which shows that the critical velocity of the performance degradation of a liquid valve can be increased by improving the design of orifice structure.