OBJECTIVE： To observe clinical efficacy and safety of Qizhi qushi jianpi prescription in the treatment of chronic synovitis of knee joint in middleaged and elderly patients after debridement under arthroscope. METHODS： A total of 80 middleaged and elderly inpatients with chronic synovitis of knee joint were selected and randomly divided into treatment group and control group， with 40 cases in each group. Clinical efficacy， VAS， swelling score of modified Cincinnati knee joint score system， Lysholm score of knee joint function， the occurrence of ADR were observed in 2 groups. RESULTS： Total effective rate of treatment group （92.5％） was significantly than that of control group （77.5％）， with statistical significance （P＜0.05）. Before debridement under arthroscope， there was no statistical significance in VAS score of knee joint， swelling score and Lysholm score between 2 groups （P＞0.05）. On the first day after surgery， VAS score of 2 groups decreased significantly， and there was statistical significance compared to before surgery （P＜0.05）. One month after surgery， VAS score of 2 groups decreased significantly， and the treatment group was significantly lower than the control group， with statistical significance （P＜0.05）. Swelling score of knee joint 1 month after surgery and Lysholm score 3 months after surgery increased significantly in 2 groups， and the treatment group was significantly higher than the control group， with statistical significance （P＜0.05）. 5 patients of treatment group suffered from stomach discomfort， and the symptom was relieved after adding the ingredient of comforting stomach and removing dampness through diuresis. CONCLUSIONS： Qizhi qushi jianpi prescription is effective for chronic synovitis of knee joint in middleaged and elderly patients after debridement under arthroscope， and can relieve pain， remove swelling and recover knee joint function with good safety.