An accurate foot end impact kinetic model is an important prerequisite for designing a bipolar crown foot end buffer mechanism. Based on spring damping model and foot-ground interaction mechanical model, a foot impact kinetic model is established considering the bipolar buffer of the ground-contact sensing spring and the approximate complete plastic deformation of the ground. The accuracy of the model and the feasibility of buffering are verified by assigning various parameters in the model using the existing experimental data. The influence of stiffness and damping on buffering effect is studied by controlling variables, which provides theoretical basis for optimizing foot buffering element of bipolar crown buffering.