Based on the theoretical foundation of“ascending the clear and descending the turbid”，to investigate the pathogenesis of slow transit constipation（STC）by studying aquaporin-3（AQP3），aquaporin-4（AQP4）and aquaporin-9（AQP9）in the colon of rats with STC.

Sixty clean grade SD rats were provided by the Animal Experimental Center of North Sichuan Medical College.They were randomly divided into normal group，model group，itopride group，high，medium and low dose groups of Baizhu（Atractylodis Macrocephalae Rhizoma）.Firstly，a rat model of STCwas established，and its therapeutic effect was observed by administering the corresponding medication.The contents，distributions and expressions of AQP3，AQP4 and AQP9 in the colon of rats in each group were detected by immunohistochemistry，q-PCR and Western blot methods，and the average optical density（MOD）value of the region was measured.

After modeling，the content of AQP9 decreased，and the distal colon tissue decreased more significantly，while the content of AQP3 increased，and the proximal colon tissue became more significant.The content of AQP4 in colon tissue also increased significantly.After drug intervention treatment，the AQP4 contents in the high dose group of Baizhu（Atractylodis Macrocephalae Rhizoma）and the itopride group significantly decreased，the AQP3 content in the proximal colon significantly decreased，and the AQP9 content in the distal colon significantly increased，with statistically significant differences.There was a decreasing trend in proximal AQP3 and an increasing trend in AQP9 content in the distal colon of the medium and low dose groups of Baizhu（Atractylodis Macrocephalae Rhizoma），but the difference was not statistically significant.

An increase in AQP3 content（proximal colon），a decrease in AQP4 content（whole colon）and a decrease in AQP9 content（distal colon）may be one of the pathogenesis of STC.Baizhu（Atractylodis Macrocephalae Rhizoma）down-regulates the expressions of AQP3 and AQP4，and up-regulates the expression of AQP9，which may be one of the mechanisms by which it exerts its“ascending the clear and descending the turbid”effect to treat STC.