Objective To investigate the clinical effect of hyaluric acid sodium injection and functional exercises on patients with comminuted fracture of tibia plateau after reposition. Methods 134 patients with comminuted fracture of tibia plateau after reposition were randomized into the observation group and the control group with 67 cases in each group. The observation group received 2ml of hyaluric acidsodium injection into the knee joint cavity with 1％ lidocaine once a week and 3 times totally. At the same time active and passive functional exercises were applied. The control group was only given routine nursing. The knee function was evaluated by Lysholm Scale 4 months after operation and the results were compared. Results The score of the observation group was higher than that of the control group(P＜0.01).Conclusion The hyaluric acid sodium injection and functional exercises could improve the healing of joint cartilage and contribute to the rehabilitation of joint function in patients with comminuted fracture of tibia plateau after reposition.