Abstract: Gives a research method for the throttle aperture when the annular slice deformation of hydropneumatic spring is considered. The flow equation of aperture under the turbulence state is deduced using the boundary layer theory, and the correctness and precision of the equation validated when compared with CFD. The rules that different structure parameters of aperture influence on the pressure are studied. Mathematical model of hydropneumatic spring is set up through the above equation and the gas state equation. Relationship of elastic force and total export output force following the displacement are studied. Correctness of the model are validated compared with the experimental data, and practicability of the turbulence flow equation is explained. The analytical equation and conclusion can offer reference to the design of the throttle valve of hydropneumatic springs.