Abstract: OBJECTIVE To study the pharmacological effect of Agkistrodon aqueous extract on osteoarthritis(OA) in rats. METHODS SD rats were randomly divided into 3 groups:normal group, model group and Agkistrodon group, 10 rats in each group. Except the normal group, the OA pain model was established by using the iodoacetic acid to inject the joint cavity(50 μL). After 48 h, the Agkistrodon group were injected with Agkistrodon aqueous extract(100 μg·mL^-1) in articular, and the model group were injected with the same amount of saline, once a week, for four consecutive weeks. The numerical changes of the paw withdrawal themal latency of the rats were measured every week, and observed the pain of the knee joint. After 4 weeks, the joint was taken for pathological section with staining so that the pathological changes of the knee joint were observed. The rat chondrocytes were cultured and the effect of Agkistrodon aqueous extract on the proliferation of cartilage cells was evaluated by CCK-8 method. RESULTS The OA pain model was established successfully. Compared with model group, the threshold of pressing pain and heat pain in Agkistrodon group were significantly increased(P<0.01); cartilage basically returned to normal, chondrocytes and cartilage matrix closed to normal levels, only had a small amount of hypertrophic chondrocytes; Mankin score significantly decreased(P<0.01); the chondrocyte viability significantly increased(P<0.01). The above index in Agkistrodon group were closed to normal group. CONCLUSION Agkistrodon acutus aqueous extract can significantly ameliorate joint pain and repair cartilage injury in OA rats. The mechanism is related to the promotion of cartilage cell proliferation and can be used in clinical OA auxiliary intervention.