Abstract：Objective：To observe the effect of the intervention of the external application of Natrii Sulfas combined with therapeutic manipulation for tendon injury on patients with knee osteoarthritis(KOA) after knee arthroplasty. Methods：A total of 84 patients with KOA after knee arthroplasty were selected and divided into the control group and the observation group according to the random number table method， with 42 cases in each group. The control group was given routine basic treatment after surgery， and the observation group was additionally given the intervention of external application of Natrii Sulfas and therapeutic manipulation for tendon injury based on the treatment of the control group. Before and after treatment， the degree of pain， circumference of affected limbs and knee joint function in the two groups were compared. Results： Before surgery and the first day after surgery，there was no significant difference being found in the comparison of the score of Visual Analogue Scale(VAS) between the two groups(P＞0.05). The third and seventh days after surgery，the scores of VAS in the observation group were lower than those in the control group(P＜0.05). Before surgery and the first day after surgery， there was no significant difference being found in the comparison of the circumference of affected limbs between the two groups(P＞0.05). The third and seventh day after surgery，the circumference of affected limbs in the observation group was shorter than that in the control group(P＜0.05). Before treatment， there was no significant difference being found in the comparison of the knee scores in Hospital for Special Surgery(HSS) and knee range of motion(ROM) between the two groups (P＞0.05). After treatment， the HSS and ROM in the two groups were increased when compared with those before treatment， and the HSS and ROM in the observation group were higher than those in the control group(P＜0.05). Conclusion： The intervention of the external application of Natrii Sulfas combined with therapeutic manipulation for tendon injury on patients with KOA after knee arthroplasty has a good effect，which can relieve the pain，reduce the limb swelling， and improve the knee function.