Objective To establish a thoracolumbar model by three-dimensional finite element analysis, and to compare the stress conduction and distribution of screw-rod system and anterior edge of vertebral body in flexion, extension, rotation and lateral bending between modified partial pedicle subtraction osteotomy and SRS-Schwab four-stage osteotomy. Methods A T₁₁-L₃ model of normal male spine was established using computed tomography (CT) data. L₁ was used as the operative vertebral body, and the three-dimensional finite element models were established for SRS-Schwab four-stage osteotomy (A operation), modified partial pedicle subtraction osteotomy with preservation of 1/3 inferior wall of pedicle (B1 operation) and modified partial pedicle subtraction osteotomy with preservation of 1/2 inferior wall of pedicle (B2 operation). Titanium mesh cage was used to support the anterior edge of vertebral body. The total stresses, the range of motion of each intervertebral space and the stress of each implant in flexion, extension, rotation and lateral bending were compared between the three-dimensional finite element models of A, B1 and B2 operations. The stresses of titanium cage implantation part, residual vertebral body, and residual accessory structure of vertebral body and screw-rod system were compared. Results During flexion, extension, rotation and lateral bending, the total stress of B2 operation was the lowest (205.6 MPa), followed by B1 operation (207.0 MPa), and that of A operation was the highest (217.0 MPa). The range of motion of each intervertebral space was similar among the three surgical methods. During flexion, extension, rotation and lateral bending, the stresses of the anterior titanium cage implantation part and remaining accessory structure and screw-rod system of posterior vertebral body of B2 operation were the lowest (22.2, 187.7, 105.8 and 141.6, and 75.4, 168.4, 75.9 and 214.8 MPa, respectively), and the stresses of A operation were the highest (27.3, 241.8, 133.4 and 188.0, and 97.5, 216.4, 98.5 and 243.0 MPa, respectively). And they were lower than yield stress and tensile limit of titanium alloy (760 and 860 MPa, respectively). Conclusion The modified partial pedicle subtraction osteotomy with preservation of 1/2 inferior wall of pedicle (B2 operation) has advantage in reducing the stress of surgical segment, especially in reducing the stress of implant, so as to decrease the risk of breaking nail and rod. However, it is similar to SRS-Schwab four-stage osteotomy in preserving the range of motion of intervertebral space.