Objective To compare the stability of multi-rod structures with double-headed screws and traditional connectors in posterior three-column osteotomy of the spine using finite element analysis. Methods A finite element model of the T3-L4 thoracolumbar spine was constructed based on postoperative computed tomography (CT) data of patients with severe kyphosis. Based on the patient’s standard two-rod model (2R), a double-headed screw multi-rod structure model (4R-DHS) and a traditional connector multi-rod structure model (4R-TC) were constructed. The two models were evaluated under 300 N follower load and 7.5 N·m moment load, and the stability, maximum von Mises stresses on the main rods, and stress distributions of the two multi-rod structures were analyzed. Results There was little difference in the stability between the two multi-rod structures. Compared with 4R-TC, 4R-DHS showed a decrease in the maximum von Mises stresses on the main rods during all motions (the stress decreased by 7.2%, 8.8%, 8.7%, 18.5%, and 16.9% during flexion, left lateral bending, right lateral bending, left axial rotation, and right axial rotation, respectively) and more uniform stress distribution, except for a slight increase in the maximum von Mises stresses on the main rods during post-extension. Conclusions The double-headed screw multi-rod structure can reduce the maximum stress on the main rod compared with the traditional connector multi-rod structure, and there is no problem with stress concentration on the main rod near the connector, which can more effectively reduce the risk of internal fixation failure.