In order to evaluate the influence of human body factors on stability of hip prosthesis accurately, some factors such as bone density of human body, body mass, walking step size, the height of human and the size of lifted foot are considered. Mathematical model of micro displacement of hip prosthesis is set up, applying the knowledge of human biomechanics and elasticity mechanics, with which the objective of stability of hip prosthesis is concerned. Sensitivity curves of influence factors are drawn in Matlab based on principle of sensitivity analysis. Meanwhile, each sensitivity function expression of factors is obtained through fitting the data in curves. The sensitiveness of objective and influential percentage of each factor is obtained with basic value of five factors above. The results show that the greatest influence on stability of hip prosthesis is bone density of human body, followed by walking step size, body mass, the height of human and the size of lifted foot. It is good to be given instruction and reference for clinical use of hip prosthesis to research on the influence of bone density of human body, body mass, walking step size, the height of human and the size of lifted foot.