PURPOSE: The study's objective was to assess the effect of the screw insertion depth into fractured vertebrae in treating thoracolumbar fractures. MATERIALS AND METHODS: This was a retrospective analysis of 92 patients with thoracolumbar fractures from December 2018 to February 2020. Patients had AO type A2, A3 thoracolumbar fractures. The patients were divided into two groups according to the screw insertion depth. The vertebral wedge angle (VWA), Cobb angle (CA), anterior vertebral body height (AVBH), middle vertebral body height (MVBH), visual analog scale (VAS) score, and Oswestry Disability Index (ODI) were compared preoperatively and at one week and 12 months postoperatively. The correlation between Vertebral height loss and potential risk factors, such as sex, age, BMD and BMI was evaluated. RESULTS: Compared with the preoperative data, the postoperative clinical and radiographic findings were significantly different in both groups, But no significant difference between the two groups at 1 week. At 1 year postoperatively, there was a significant difference in the CA (p < 0.0001), VWA (p = 0.047), AVBH (p < 0.0001), MVBH (p < 0.0001), VAS score (p < 0.0001), and ODI (p < 0.0001) between the two groups, Except for age, bone density and other influencing factors the long screw group had better treatment results than the short screw group. CONCLUSION: A longer screw provides greater grip on the fractured vertebral body and stronger support to the vertebral plate. The optimal screw placement depth exceeds 60% of the vertebral body length on the lateral view.