Objective To investigate the changes of renal medulla aquaporin 2 expression and morphological changes of epithelia of collecting tube after bile duct recanalizaiton operation. Methods Thirty rats were divided into two groups randomly. Common bile duct ligation was performed on 20 experimental rats with silicon tubes 2 mm in extre-diameter, and sham operation on the other 10 rats. Seven days later, bile duct recanalizaiton was performed on obstructive jaundice group and sham operation on contrast group. Experimental rats were divided into two subgroups randomly. Half of them were killed immediately and the others would be killed 24 hours later. Serum of each rat was collected to detect hepatic function and renal function. Renal medulla was fixed for microscopic examination and was kept in the -80 ℃ refrigerator for aquaporin 2 expression measurement by Western blot technique. Results All of the animals accomplished the experiment smoothly. Golden ascites were found in the rats of obstructive jaundice group. Twenty-four hours after recanalization, serum bilirubin levels decreased 〔(45.95±8.39) μmol/L〕, P＜0.01, and there was no significant change in blood urine and creatine level. Compared with sham operation group (21 966.20±1 544.70), expression of aquaporin 2 decreased significantly after common bile duct ligation in obstructive jaundice group (15 665.30±1 181.85), P＜0.01. After recanalizaion, the expression of aquaporin 2 in obstructive jaundice group increased (19 490.80±4 239.32), P＜0.01. Conclusion Common bile duct obstruction would lead to epithelium injury of renal collecting tube, and down regulate the aquaporin 2 expression.