Abstract: Hydraulic shock absorber is a key device of sled impacttest for automobile components. This paper proposes a mechanical model ofhydraulic shock absorber for sled impact test based on the law oforifice flow, and discusses the factors influencing the model. Afterthe optimization of these factors, simulation curves can be made, whichagree with the test curves very well. The simulating process provides areliable basisof setting up a model for this kind of absorber and adjusting theabsorber to simulate the real car crash process.