Objective The stability of multi-rod structure with double-headed screws and multi-rod structure with conventional connectors in posterior three-column osteotomy of the spine were compared by means of finite element analysis. Methods A finite element model of T3~L4 thoracolumbar spine was constructed based on the postoperative CT data of patients with severe kyphotic kyphosis. On the basis of the patient's standard two-rod model (2R), the double-headed screw multi-rod structure model (4R-DHS) and the traditional connector multi-rod structure model (4R-TC) are constructed. The two models were evaluated under a 300N follower load and a 7.5N·m moment load to analyze the stability, maximum Von Mises stresses on the main rods, and stress distributions of the two multi-rod structures. Results There was little difference in the stability between the two multi-rod structures. Compared with 4R-TC, 4R-DHS shows decreases in the maximum Von Mises stresses on the main rods during all motions (7.2% in flexion, 8.8% in left lateral bending, 8.7% in right lateral bending, 18.5% in left-axial rotation, and 16.9% in right-axial rotation) and a more uniform distribution of stresses, except for a slight increase in 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 of stress concentration on the main rod near the connector, which can more effectively reduce the risk of internal fixation failure.