OBJECTIVE: To investigate the effect of two-dimensional computer-assisted surgical navigation on the consistency of bilateral lumbar pedicle screw placement. METHODS: From January 2004 to December 2009, 1355 patients underwent lumbar posterior pedicle screw internal fixation, and 743 patients were assisted with 2D computer-assisted surgical navigation for nail placement (navigation group) and 612 patients were assisted with X-ray fluoroscopy for nail placement (fluoroscopy-assisted group). Image-pro plus 5.0 software was used for image measurement and analysis of standard lumbar frontal and lateral radiographs on the 7th postoperative day to compare the consistency of bilateral pedicle screw placement in the two groups. The angle between the bilateral pedicle screw axes and the upper endplate of the vertebral body where they were located (α angle) and the angle between the bilateral pedicle screw axes (γ angle) were measured on the lumbar lateral radiographs; whether the pedicle screws were in the pedicle was determined on the lumbar orthogonal radiographs, and the accuracy rate of the pedicle screws being all in the pedicle was calculated. RESULTS: The mean left α-angle side of the navigation group was 3.89±0.47°, the mean right α-angle was 3.94±0.37°, and the differences of bilateral α-angle in each segment from L1 to S1 were not statistically significant; the mean left α-angle of the fluoroscopy-assisted group was 4.32±1.47°, the mean right α-angle was 4.37±1.59°, L2 (left 4.55±1.27°, right 5.12±1.87 °) and L4 (4.22±1.89° on the left and 6.62±1.97° on the right) segments had statistically significant differences in bilateral α angles, while all other segments had no statistically significant differences in bilateral α angles. The γ angle of the navigation group (2.32±0.27°) was smaller than that of the fluoroscopy-assisted group (3.32±1.51°), and the difference was statistically significant. The accuracy of nail placement was 91.5% (3604/3938) in the navigation group and 87.6% (2426/2768) in the fluoroscopy-assisted group, and the difference was statistically significant. CONCLUSION: The accuracy of two-dimensional computer-assisted surgical navigation for pedicle screw placement is higher than that of fluoroscopy-assisted nailing, which can improve the consistency of bilateral lumbar pedicle screw placement.