Objective To investigate the effects of extracts of Pinellia ( EP) on a rat model of airway mucus hypersecretion induced by LPS. Methods Thirty Wisatr rats were randomly divided into 5 groups, ie. a blank group, a model group, and three EP groups treated with different doses of EP. There were 6 rats in each group. Airway mucus hypersecretion model was established by intratracheally instillation of LPS in the model group and three EP groups. The rats in three EP groups were orally administered with EP at dosages of 10 g/kg, 30 g/kg and 60 g/kg respectively for 4 days. The expression of Mucin 5AC ( MUC5AC) protein in airway was assayed by immunohistochemistry. The mRNA expressions of MUC5AC and Aquaporin-5( AQP-5) in lung tissue were detected by RT-PCR. ELISA technique was performed to detect TNF-αin bronchoalveolar lavage fluid( BALF) . Results LPS significantly stimulated the mRNA and protein expression of MUC5AC in lung and TNF-αlevel in BALF, and inhibited the expression of AQP-5 mRNA in lung. The EP at dosages of 10 g / kg and 30 g/ kg had little effect on mucus hypersecretion. While 60 g/kg of EP could significantly inhibited the expression of MUC5AC, and decreased the release of TNF-α in BALF. The AQP-5 mRNA was also up-regulated by 60 g /kg of EP. The expression of MUC5AC mRNA was positively correlated with level of TNF-α( r = 0. 948, P lt;0. 05) ; AQP-5 mRNA was negatively correlated with MUC5AC mRNA and TNF-α( r = - 0. 955, P lt; 0. 05; r = - 0. 909, P lt; 0. 05) . Conclusion EP ( 60 g/ kg) can significantly attenuated airway mucus hypersecretion in rats.