Objective To investigate the effectiveness of double-plane high tibial osteotomy in treatment of medial compartment osteoarthritis. Methods The clinical data of 65 patients with medial compartment osteoarthritis who were treated with double-plane high tibial osteotomy between January 2014 and January 2017 was retrospectively analyzed. There were 28 males and 37 females. The age ranged from 46 to 75 years with an average of 53.2 years. There were 30 cases in the left knee and 35 cases in the right knee. The disease duration was 3-7 years (mean, 4.0 years). The patients had different degrees of pain in the knee joint and difficulty walking. The knee joint compression test was positive. The knee joint function was evaluated by Hospital for Special Surgery (HSS) score and knee society score (KSS) clinical and functional scores. The visual analogue scale (VAS) score was adopted to pain measurement. The healing of osteotomy was observed by X-ray films during follow-up; the femur tibia angle (FTA), posterior tibial slope (PTS), medial proximal tibial angle (MPTA), and knee varus angle (KVA) were also calculated. Results All the incisions healed by first intention after operation. Only 1 case had numbness of the toe, and the symptoms disappeared after symptomatic treatment. All patients were followed up 13-18 months with an average of 15.4 months. X-ray examination showed that all patients had bone healing at 12 weeks after operation. There were significant differences in MPTA, FTA, PTS, and KVA between pre- and post-operation (P<0.05). There was no significant difference in above parameters among 1 week, 6 months, and 12 months after operation (P>0.05). There was no loosening and rupture of the fixator during the follow-up. The HSS score and KSS clinical and functional scores at 12 months after operation were significantly higher than those before operation (P<0.05). The VAS scores at 1 week, 6 months, and 12 months after operation were significantly lower than that before operation (P<0.05). Conclusion Double-plane high tibial osteotomy for medial compartment osteoarthritis can effectively relieve pain symptoms and improve joint function.