Abstract: Objective: To explore the effects of medical ozone combined with sodium hyaluronate injection in the treatment of the knee osteoarthritis after arthroscopic surgery.Methods: One hundred and twenty patients with knee osteoarthritis were randomly divided into the control group and treatment group(60 cases each group).The control group and treatment group were treated with sodium hyaluronate injection of articular cavity and sodium hyaluronate combined with medical ozone injection of articular cavity after arthroscopic surgery,respectively.The injection time and frequency in two groups were the same.The curative effects between two groups were compared in 3,6 and 12 months after treatment.Results: Compared with before treatment in two groups,their Lysholm scales increased significantly in 3,6 and 12 months after treatment(P<0.01).The Lysholm scales in treatment group in 6 and 12 months after treatment were better than those in control group(P<0.05 and P<0.01).Conclusions: The effects of medical ozone combined with sodium hyaluronate injection in the treatment of the knee osteoarthritis after arthroscopic surgery are good.