Objective To elucidate the biomechanical foundation of Acetabular Tridimensional Memoryalloy - Fixation System (ATMS) for treatment of acetabular fractures. Methods The experiment consists of two parts, one is to study the stability of the fixed acetabulum posterior wall with ATMS, the other is to research the fitness of the femoral head and the fixed acetabulum as well as the stress distribution. Six fresh pelvis and femur specimens were divided into two groups, the experimental group consists of the left sides, and the control group consists of the right sides. After the fractures of the posterior wall were made, the acetabular fragments were replaced and were fixed by ATMS in the experimental group, whereas fixated by the plates and screws in the control group. A adjustable jig which can be adjusted in multiple directions was made. The specimens were loaded from 100N to 500N in three status: flexion, extension, and erection. The fixation in latitude and longitude of the two groups was compared, and the stability of fixation of posterior wall of the acetabulum was analyzed. The two groups were then loaded to 1000N in erection status. And the pressure-sensitive slices were used to calculate the contact area, the mean pressure and maximum pressure of anterior wall, superior aspect and posterior wall of the acetabulum, and to analyzed the fitness of femoral head and the acetabulum as well as the stress distribution. Results There was no significant difference between the two groups in the different status with different loads. It also showed that when loaded with 1000N, there was no significant difference between two groups in the contact area, mean pressure and maximum pressure of every part of acetabulum. Conclusion Fixation of posterior wall of the acetabulum with ATMS had good stability and good fitness and stress distribution of the femoral head and the repaired acetabulum.