Studying the dynamic regulation of the landing impact forces and influence factors for landing impact is the basis of analysis of the dynamic stability of robots. Considering that the rubber mat in landing phase is in large deformation during the landing process of robot, the dynamic model and simulation model of the landing impact process that consists of the dynamic models of robot's leg and body, the viscoelastic model of rubber floor in large deformation and the thermodynamics model of gas in cylinder chambers are built. In addition, the simulation results show that the change of foundation elastic reaction and damping force in the compression phase makes impact force increase quickly, reach a maximum and then decrease, that the maximum impact increases as the falling height and the storage module of rubber increase, decreases as the thickness of the rubber increases, and that the larger ratio, the smaller maximum impact when the ratio of the dissipative energy scale factor to the vibration frequency is less than 0.01, and the larger ratio, the larger maximum impact when the ratio is more than 0.01. The maximum relative error of simulation results and experiment results of the robot for 0.1 m free fall is less than 7.6%, which verifies the simulation results.