Aim To investigate whether Hcy influenced the intestinal mucosal permeability by regulating MEK-ERK-MLCK pathway. Methods SD rats were divided into 4 groups:normal group, normal+Hcy group, TN-BS/ethanol group, TNBS/ethanol+Hcy group. Experi-mental colitis model with hyperhomocystinemia was es-tablished in rats with intracolonic administration of TN-BS and subcutaneous injection of Hcy. The colonic mucosal tissue was collected for histopathological exam-ination and activity of myeloperoxidase ( MPO ) . The protein expression of MLCK, p-MLCK, MEK, ERK and p-ERK in intestinal mucosal tissues was examined by Western blot method. The mRNA expression of ML-CK was examined by RT-qPCR method. Result Com-pared with the normal group and TNBS group, the DAI and HI scores and the MPO activity were increased in TNBS/ethanol+Hcy group ( P <0. 01 ) . Western blot and RT-qPCR showed that expression of MLCK, p-ML-CK, MEK, ERK and p-ERK increased in small intes-tine in TNBS/ethanol+Hcy group. Conclusion Hcy can increase intestinal permeability in TNBS-induced colitis rats by regulating the expression of MEK-ERK-MLCK signal pathway.