Objective To analyze the influence of ligaments surrounding sacroiliac joints (SIJs) on stability of SIJs by finite element method. Methods The finite element lumbar spine-pelvis-femur model was established. Based on this normal model, all SIJ ligaments in both sides were removed in turn, to establish models without iliolumbar ligaments, sacroiliac anterior ligaments, sacroiliac posterior ligament, sacrotuberous ligaments, sacrospinous ligaments, sacroiliac interosseous ligaments, respectively. The models were used to simulate physiological motions of the spine. The range of motion (ROM) and average stress on the left and right SIJs were analyzed and compared with the normal models. Results Compared with the normal SIJ model, no significant differences in the ROM of bilateral SIJs were found in the models without sacrotuberous ligaments, sacrospinous ligaments and sacroiliac posterior ligaments; for the model without acroiliacinterosseous ligaments, there was no significant difference in the ROM of the left SIJs under spinal right rotation and ROM of the right SIJs under spinal extension, but the ROM of bilateral SIJs increased significantly under the other spinal physiological activities. Under the physiological activities of the spine, the average stress of the SIJ surface in the left and right sides of the model without acroiliacinterosseous ligaments significantly decreased. Conclusions Of all the sacroiliac ligaments, the sacroiliac interosseous ligaments showed the maximum influences on the stability of SIJs. The research findings are helpful to investigate the mechanism of SIJ subluxation and provide certain theoretical basis for clinical treatment of SIJ subluxation.