Objective To investigate the method and efficiency of supracondylar dome osteotomy of femur combined with arthroscopy for the treatment of the adult valgus deformity of knees. Methods From September 2008 to May 2012, 32 patients (35 knees) with valgus deformity of knees were treated with supracondylar dome osteotomy of femur combined with arthroscopy. The study group included 7 male and 25 female (average age: 43 years). The pre-operative HSS knee score was an average of 60.46. The weight-bearing knee joint AP & LAT and the full-length AP view of the lower extremity were examined before and after operation. At the same time , the femoral angle and femoral-tibial angle were measured and evaluated. The internal fixation was taken out in an average in 12 months. All the patients were followed-up and the change of the correction angles , the function of the knee and the condition of bone healing was recorded. Result The follow-up time was an average of 24 months. All the patients got a satisfied correction of the deformity, good bone union and obvious improvement of joint function. The postoperative HSS knee score was an average of 85.40. Conclusion The supracondylar dome osteotomy of femur combined with arthroscopy is a safe, reliable and effective strategy for the treatment of the adult valgus deformity of knees.