Abstract: Objective:To explore the expression of the Toll-like receptor 4(TLR4),myeloid differentiation factor-88(Myd88) and nuclear factor-b(NF-b) and interleukin-1(IL-1) in colon tissue and peripheral blood of ulcerative colitis(UC) rat model and determine the role of TLR4/NF-b signaling pathway on the pathogenesis of UC, and provide new ideas to know the development of UC rat and therapy using pathway blocking drugs. Methods:Forty Sprague-Dayley(SD) rats were randomly divided into Group A(the model group,20 rats) and Group B(the control group,20 rats). The model of UC rats with cell immunoreactivity were made using compound method(Trinitrobenzene sulfonic acid and ethanol),which were evaluated by histology injury and HE staining of colonic mucosa. The expression of TLR4,Myd88 and NF-b of colonic mucosa were detected by using RT-PCR, and the expression levels of IL1 in sera were detected by ELISA. Results:Compared with Group B, the histopathologic changes, macroscopical changes and the expression of TLR4,Myd88,NF-b in colonic mucosa and IL-1 levels in sera of Group A were significant higher(P 0. 01). Conclusions:The expression of TLR4,Myd88 and NF-b in the colonic mucosa of UC rat is significant higher than that in normal group and TLR4 expression may induce the expression of NF-b mRNA of its downstream genes, which can lead to the release of inflammatory cytokines.