Objective To explore the clinical efficacy of Wanying Xiaotong Plaster,in the treatment of knee osteoarthritis(KOA)with Cold-Dampness stagnation.Methods 120 patients who suffered KOA with Cold-Dampness stagnation treated at the Third Affiliated Hospital of Zhejiang Chinese Medical University from January 2021 to December 2022 were retrospectively analyzed.They were divided into an observation group and a control group according to different treatment methods.60 patients in the observation group received Wanying Xiaotong Plaster combined with basic treatment,while 60 patients in the control group received both the external washing formula from the orthopedic department and basic treatment.After continuous intervention for 2 weeks,the knee joint range of motion,function,and traditional Chinese medicine syndromes of patients from the two groups were evaluated and statistically analyzed.Results Before the treatment,there was no statistically significant difference(P>0.05)in the scores of 30-Second Chair Stand Test(30CST),Hospital for Special Surgery(HSS),and traditional Chinese medicine syndromes between the two groups of patients.After 2 weeks of the treatment,the scores of both groups of patients showed significant improvement compared to before the treatment(P<0.01).The effective rate of the observation group(96.7%)was better than that of the control group(86.7%)(P<0.05).The improvement of the observation group's 30CST scores,HSS scores,and traditional Chinese medicine syndrome scores were better than that of the control group(P<0.05).During the treatment period,no patients reported adverse events.Conclusion Wanying Xiaotong Plaster is safe and effective in the treatment of knee osteoarthritis with Cold-Dampness stagnation,and is worthy of further clinical promotion.