The structure of a kind of low impact separation device was introduced,and the cold-gas drive separation test was analyzed.Based on energy conservation formula and air dynamics principle,the mathematical model of separation device during cold-gas drive separation process was derived.The cold-gas drive separation process of a low impact separation device was simulated and tested.The simulation results agree well with experimental data.The effects of some parameters on peak pressure were simulated.The simulation results can provide reference for design and optimization of separation device.