Abstract: Based on LNZN model, the modified model was a two-mass-spring-damping model based on LNZN model.The influence of shoe performance and ground stiffness on impact force is discussed.The performances of shoes and floors were not considered in the LNLN model. Therefore, in this study, the LNLN model was modified to calculate the impact force during running with a two-layer mass-spring-damping model. The first layer was the sole and the second layer was the ground. According to the ground rigidity and shoe sole performance, the equation of motion was established and the running impact force was calculated. The calculation results showed that the ground reaction force was consistent with the cushioning force of shoes, and the calculation results of modified model were consistent with the experimental results. Besides, the calculation results of load rate and peak dynamic value of model were basically consistent with the experimental results, which indicate that the modified model is successful and can be used to calculate the impact of the ground on the human body during running.