Abstract: To explore the effect of estrogen on the intestinal mucosal barrier function of the rat， eighteen female Wistar rats were induced oestrous synchronizotion and then were divided into three groups in the dioestrus: Control group (Shame operation)， OVX group (Ovariectomy)， and OVX+E₂ group (Ovariectomy and injecting with 100 μg/kg·d estradiol benzoate). After a week， the structure of mucosals epithelium and the number of intraepithelial lymphocytes and goblet cells were observed by light microscope. The results showed that in the OVX group， the villus was atrophic， the villus height and the ratio of villus height to the depth of crypt decreased， and the number of intraepithelial lymphocytes and goblet cells decreased too. There were significant differences between control group and OVX group(P＜0.05)， and between OVX group and OVX+E₂ group(P＜0.05). There were also differences between control group and OVX+E₂ group， but some indexes between them were not significant. This study indicated that the intestinal mucosal barrier function was greatly damaged in ovariectomy rat， and proper dosage of estradiol benzoate (100 μg/kg·d) would improve the small intestinal mucosal barrier function of ovariectomy rat to some degree.