OBJECTIVE： To observe the effect of Banxia Xiexin decoction on nuclear transcription factor κB p65 （NF-κB p65）， NF-κB inhibitory protein α （IκB-α） and Toll-like receptor 4 （TLR4） in colon tissue of rats with ulcerative colitis （UC）， and explore the possible mechanism for UC treatment. METHODS： Rats were randomly divided into normal group （normal saline）， model group （normal saline）， Sulfasalazine enteric coated tablet （SASP， positive group， 0.3 g/kg）， Banxia Xiexin decoction low-dose， medium-dose， high-dose groups （3.9， 7.8， 11.7 g/kg）， 8 in each group. Except for normal group， other groups were used trinitrobenzene sulfonic acid-ethanol method to reduce UC model. After modeling， they were administrated， ig， once a day， for 3 weeks. After administration， NF-κB p65， IκB-α， TLR4 mRNA and protein expressions in colon tissue of rats in each group were detected. RESULTS： Compared with normal group， NF-κB p65， IκB-α， TLR4 mRNA and protein expressions in colon tissue of rats in other groups were significantly increased （P＜0.05）. Compared with model group， NF-κB p65， IκB-α， TLR4 mRNA and protein expressions in colon tissue of rats in each administration group were significantly decreased （P＜0.05）； showing certain dose-dependent， and the decreasing degree of above indexes in colon tissue of rats in Banxia Xiexin decoction high-dose group were higher than SASP group （P＜0.05）. CONCLUSIONS： Banxia Xiexin decoction can down-regulate the NF-κB p65， IκB-α， TLR4 mRNA and protein expressions in colon tissue of UC rats， which may be one of the mechanisms for UC treatment.