Objective To observe the clinical effects of magnified pedicle subtraction osteotomy (mPSO) via the posterior approach combined with biomimetic bone graft fusion and internal fixation for the treatment of thoracolumbar Kummell's disease and kyphosis.Methods A total of 11 patients with thoracolumbar Kummell's disease and kyphosis deformity were treated at our department from March 2012 to June 2016.They all underwent mPSO via the posterior approach combined with biomimetic bone graft fusion and internal fixation.They were 3 men and 8 women with an average age of 61.2 years.The clinical effects were evaluated according to visual analogue scale (VAS),Japanese Orthopaedic Association (JOA) scoring,American Spinal Injury Association (ASIA) grading,cobb angle correction and rate of bone graft fusion at preoperation and 2 weeks,1,3,6 and 12 months after operation.Results All the patients were followed up for an average of 11.4 months (from 10 to 13 months).The VAS scores (2.1 ±0.5 points and 1.1 ±0.2 points),JOA scores (23.6 ±3.8 points and 25.5 ±3.2 points) and cobb angles (8.1°± 1.5° and 13.8°±2.1°) at 2 weeks after operation and final follow-ups were significantly improved from their preoperative values (8.1 ± 0.6 points,12.1 ± 3.6 points and 51.3° ± 9.8°,respectively) (P ＜ 0.05).However,there were no significant differences between 2 weeks after operation and the final follow-up in terms of the above values (P ＞ 0.05).The ASIA grading was improved from preoperative grade C to postoperative grade D in one case,and from preoperative grade D to postoperative grade E in 3 cases.At final follow-ups,bony fusion was observed at all the bone graft sites,with a fusion rate of 100％.Conclusion mPSO via the posterior approach combined with biomimetic bone graft fusion and internal fixation is a good treatment for patients with thoracolumbar Kummell's disease and kyphosis deformity.