Objective To investigate the effect of sodium hyaluronate injection combined with platelet-rich plasma in the treatment of patients with knee osteoarthritis. Methods A total of 120 patients with knee osteoarthritis who were treated in our hospital from July 2019 to July 2021 were collected and randomly divided into control group and observation group,60 cases each.The patients in the control group were injected with platelet-rich plasma(4 mL),and the patients in the observation group were injected with sodium hyaluronate(2 mL)combined with platelet-rich plasma(3.5 mL),once a week,3 times as a course of treatment,total 2-3 courses of treatment.The knee joint function,clinical efficacy and complication rates of the two groups were compared. Results ①Intra-group comparison:the average Lysholm knee joint scores were significantly increased in 2 months,3 months and 6 months after treatment,P<0.05. ②Comparison between groups:before and 2 months after treatment,the average Lysholm knee joint scores of the two groups were significantly increased (P<0.05). After 3 months and 6 months treatment,the comparison of the average Lysholm knee score between the two groups were statistic significant (P<0.05).The Lysholm knee joint scores in both groups were improved compared with those before treatment (P<0.05). Three months after treatment,the pain score(18.92±4.11, 17.61±3.83)and swelling score(10.64±2.82, 9.66±1.21)in the observation group were significantly higher than those in the control group(14.02±3.52, 13.54±3.21, 9.62±2.63, 8.71±1.93, P<0.05).The total clinical effective rate of the observation group was 98.33%,which was significantly higher than that of the control group (88.33%, χ²=4.821,P=0.028).After 6-month follow-up,local swelling occurred in 1 case in both groups,and no other complications occurred. Conclusions Sodium hyaluronate injection combined with platelet-rich plasma in the treatment of patients with knee osteoarthritis can effectively improve the knee joint function and reduce the pain and swelling of the patients.It is safe and worthy of popularization and application.