Objective To explore the anti-osteoporosis effect of bisphosphonates on repairing injured vertebrae after thoracolumbar fracture internal fixation through a randomized controlled study. Methods Eighty-four patients with thoracolumbar fracture treated by orthopaedic internal fixation in Department of Orthopaedics, Nanjing General Hospital from Jun. 2014 to Jun. 2015 were included, and the patients were divided into the bisphosphonate treatment group (n=42) and control group (n=42) by random number method. The patients in both groups were given the routine anti-osteoporosis drugs such as calcitriol and calcium carbonate D3 after surgery; in addition, the patients in the bisphosphonate treatment group were also given alendronate sodium D3 tablets (each containing alendronate sodium 70 mg, 1 tablet per week), while the control group received a placebo. The bone mineral density (BMD) in thoracolumbar vertebral injury area of patients in the two groups was measured and compared at 1 month, 3 months, 6 months and 1 year after surgery. Results The BMD values of patients in two groups were significantly decreased immediately after reset compared with preoperation, and then they were increased continuously in follow-up. There was no significant difference in BMD between the two groups at 1 month or 3 months after sursery (P>0.05), while the BMD in the bisphosphonate treatment group was significantly higher than that in the control group at 6 months and 1 year after surgery (P<0.05). Conclusion Bisphosphaonate drugs can accelerate the repair of vertebral osteoporosis after thoracolumbar fracture internal fixation, showing a good clinical application value.