To obtain the more accurate fractal model of the normal contact stiffness and research the factors influencing the stiffness, the fractal model of the contact stiffness between the joint surfaces considering the friction is established, and the corresponding stiffness formula is derived. The fractal model is based on the classical G-W (Greenwood-Williamson) statistical model and M-B ( Majumder-Bhushan) fractal model. In the following, the influence of the fractal dimension, friction coefficient, contact load, combined area on the normal contact stiffness are discussed. The research results show that the normal contact stiffness model deduced in this paper is suitable to the friction surfaces. And the influ ence of the friction coefficient between the joint surfaces on the normal contact stiffness largely depends on the size of joint surfaces. Besides, the fractal dimension, contact load, combined area also have great influence on the normal contact stiffness.