Abstract: [Objective] to investigate the effect of autologous bone transplantation on the repair of severe varus tibial medial plateau bone defect in patients with knee osteoarthritis who underwent knee surface replacement for the first time. [Methods] 180 patients with osteoarthritis with knee varus who underwent initial knee surface replacement from February 2006 to March 2019 were reviewed. Among them, 86 patients still had medial plateau bone defect after tibial steotomy and were repaired with autologous bone transplantation. According to RAND classification, 78 patients had type II bone defect, including 29 males and 49 females; There were 8 cases of type ⅲ bone defect, including 4 males and 4 females. The patients were followed up at 6 weeks, 3 months, 6 months, 12 months and 24 months after operation. X-ray examination was performed to understand the bone graft healing. The longest follow-up time was 14 years. HSS knee scoring system was used before and after operation to evaluate the postoperative clinical effect. [Results] All 86 patients were followed up after the operation. The follow-up time was 2 years to 12 years, with an average of 6 years. Except for the first patient who used autologous bone graftingfor bone defect on both knees, bone resorption and bone grafting occurred in the left knee 2 years after the operation. In addition to the loosening of the tibial prosthesis, the bone grafts of the remaining patients healed in 6-12 months without any loosening of the prosthesis. The range of motion of the knee joint increased from 75.2°±12.5° before surgery to 120.6°±21.3° after surgery. The range of motion at 1 year after surgery was statistically significant compared with that before surgery (P=0.023). The HSS score increased from 35.1 ±14.5 points before surgery to 95.4±13.2 points after surgery. Among them, 70 cases were excellent, 10 cases were good, 5 cases were general, and 1 case was poor. The excellent and good rate was 93%. The HSS score at 1 year after surgery was statistically significant compared with that before surgery (P=0.012). [Conclusion] knee surface replacement was performed in patients with knee osteoarthritis with Rand Ⅱ and Ⅲ bone defects of the medial tibial plateau. The use of autologous bone transplantation to repair the bone defects can reduce the cost, maximize the preservation of bone mass, and achieve good curative effect. It is an ideal method to repair Rand Ⅱ and Ⅲ bone defects Effective methods.