Abstract: Objective Study the stress distribution law of the area around the acetabulum during the normal gait cycle, further to explore the distribution of biology force lines of each column of the acetabulum and the thickness morphology of cortical bones. Methods The muscle and hip loads under 8 typical phases of human gait cycle are obtained through human reverse dynamics analysis, 3-d reconstruction technology is used to build the three-dimensional model of the hip bone, the finite element analysis and topology optimization of cortical bones are carried out by using the obtained loads as loading boundary conditions. Results In the support phase, the hip joint load is larger, the strain energy of the middle column accounts for 55%~69% of the total strain energy, and the stress at the top of the acetabulum is larger. In the swing phase, the hip joint load decreases and the percentage of strain energy in the middle column decreases. The different motion angles of the hip joint affect the muscle force and then affect the stress distribution on the hip bone. The obtained biology force lines of of each column of the acetabulum based on finite element method are basically consistent with biology force lines and bone trabecular arrangement proposed by anatomy, and correspond to the thicker areas of cortical bones in topology optimization simulation results. Conclusions In this paper, biology force lines of each column of the acetabulum and the distribution of the thickness morphological characteristic of cortical bones are determined by numerical simulation which can guide the placement of the internal fixation for the fracture treatment.