Objective: To compare the biomechanical properties of two screw rod and three screw rod, and to study the difference of mechanical effects of different screw rod fixation positions in pelvic minimally invasive surgery. Methods: the mechanical model of pelvis after two or three screw rod fixation was established, and the biomechanical characteristics of the pelvis in the two leg standing, healthy side single leg standing, affected side single leg standing and sitting posture were compared and analyzed by finite element simulation, and the fixation effect of three screw rod was verified by clinical experiments. Results: the two fixation methods can restore the pelvic mechanical transmission, but the stress on both sides of the pelvis is more balanced, and the displacement of the whole body and fracture surface is also lower when the three screw rod fixation is used for unilateral standing. Conclusion: three screw rod fixation has excellent effect in stability, which is more conducive to fracture recovery.