OBJECTIVE： To observe the effects of Modified Rhizoma Alismatis decoction on the expression of aquaporin 8 （AQP8） in liver tissue of hyperlipemia model rats， and to investigate the mechanism of preventing and treating hyperlipemia. METHODS： Total of 60 rats were randomly divided into blank control group （distilled water）， model group， positive control group （simvastatin 1.89 mg/kg） and modified Rhizoma Alismatis decoction high-dose， medium-dose and low-dose groups （29.56， 14.78， 7.39 g/kg， calculated by crude drug）， with 10 rats in each group. Those groups were given high-fat diet to induce hyperlipemia model and given relevant medicine intragastrically once a day for consecutive 5 weeks except that blank control group was given normal diet. After administration， the serum contents of TG， TC， HDL-C and LDL-C in rats were detected， and the pathomorphology changes of liver tissue were observed； the mRNA and protein expression of AQP8 in liver tissue were detected. RESULTS： Compared blank control group， the serum contents of TG， TC and LDL-C in model group were increased significantly （P＜0.05 or P＜0.01）， while the serum content of HDL-C was decreased significantly （P＜0.01）； pathological changes were found in liver tissue， such as irregular cell arrangement and hepatic sinusoidal hyperemia and edema； mRNA and protein expression of AQP8 in liver tissue were increased significantly （P＜0.01）. Compared with model group， above indexes of treatment groups were improved significantly （P＜0.05 or P＜0.01）； the structure of liver tissue tended to be normal and the fatty degeneration was obviously alleviated. CONCLUSIONS： Modified Rhizoma Alismatis decoction can regulate the mRNA and protein expression of AQP8 in liver tissue so as to play the effects on the prevention and treatment of hyperlipidemia.