The landing gear of the aircraft bears a large impact load during landing, which causes the internal gear of the landing gear to withstand high oil pressure and air pressure. This paper analyzes the internal pressure changes during the landing process. Firstly, based on the axial load of the buffer, the pressure formula of each cavity of the buffer is obtained. Secondly, the differential equation of landing gear landing motion is established by using the two Mass System. Finally, the landing gear buffer pressure simulation model is built by using MATLAB/Simulink. The model is used to analyze the variation of the pressure of each chamber with time and buffer stroke at different landing speeds. The influence of oil chamber pressure on the cushioning performance with different oil return areas is also analyzed. The conclusion is as follows: at different landing speeds, the pressure of each cavity presents a certain regularity at a specific moment of the landing process; the positive stroke oil return hole should not be too small, ensuring that the oil fills the oil return cavity, and the reverse stroke oil return hole cannot be too Large to ensure that the oil fills the main oil chamber；The oil pressure in the buffer during landing impact affect the stability of the plunger.