Objective To observe the effect of Haitongpi Decoction on postoperative rehabilitation of patients with chronic ankle instability treated by anatomical reconstruction of lateral ligament with allogeneic tendon.Methods From December 2020 to December 2022,42 patients who underwent anatomical reconstruction of lateral ligament with allogeneic tendon were divided into two groups randomly.The patients in the blank group completed the reconstruction of lateral tendon with allogeneic tendon and routine postoperative rehabilitation.The control group was treated with Haitongpi external washing on the basis of the blank group.The VAS pain score,AOFAS score of the ankle and hindfoot function,swing distance of pressure center and maximum dorsiflexion angle of ankle joint support period were compared between the two groups before and 3 months after operation.Results The VAS pain score,AOFAS score of the ankle and hindfoot function,swing distance of pressure center and maximum dorsiflexion angle of ankle joint support period in the two groups were better than those before operation(P<0.05).The VAS pain score,AOFAS score of the ankle and hindfoot function and maximum dorsiflexion angle of ankle joint in the control group were better than those in the control group at 3 months after operation(P<0.05).There was no significant difference in the swing distance of pressure center between the control group and the blank group at 3 months after operation(P>0.05).Conclusion Haitongpi Decoction has a significant effect on postoperative pain relief and ankle function improvement in patients with allogeneic tendon anatomical reconstruction of lateral ligament,and accelerates the recovery of patients.