Objective To establish a rat model of ovarian endometriosis (EMS) using the horn reversion method, to provide an ideal animal model for exploring the pathogenesis and treatment of EMS. Methods Fifty SPFgrade female SD rats were divided randomly into five groups: a sham group, and 1, 2, 3, and 4 weeks after surgery groups, respectively (n=10 rats per group). Apart from the sham group, an ovarian-type EMS model was established in the other groups by the uterine horn refracture method, and the modeling success rate, and ectopic foci volume and mass were observed in each group. The morphology of ectopic foci was observed by hematoxylin-eosin (HE), and expression of proliferating cell nuclear antigen (PCNA), Ki67, epithelial cadherin (E-cadherin), and neural cadherin (N-cadherin) in the uterus and ectopic foci tissues were detected by immunohistochemistry. The model was further evaluated and the degree of cell proliferation and epithelial mesenchymal transformation at different times after modeling were analyzed. Results The modeling success rates in the 1, 2, 3, and 4 weeks after surgery groups were 80%, 90%, 100%, and 100%, respectively (P>0.05). The volume and mass of the ectopic foci were significantly greater in the 3 and 4 weeks after surgery groups compared with the 1 and 2 weeks after surgery groups (P<0.01). HE staining showed endometrial epithelial cells, mesenchymal cells and a few glands in the ectopic foci tissues. Immunohistochemical staining showed that expression levels of Ki67, PCNA, and N-cadherin in uterus tissues were significantly higher (P<0.05, P<0.01) in all the model groups compared with the sham group, while expression levels of E-cadherin were significantly lower (P<0.05, P<0.01). Expression levels of Ki67, PCNA, and N-cadherin in the uterus and ectopic foci tissues were significantly higher (P<0.05, P<0.01) in the 2, 3, and 4 weeks after surgery groups compared with the 1 week after surgery group, while expression levels of E-cadherin were significantly lower (P<0.05, P<0.01). Conclusions The uterine horn reversion method can be used to establish an ovarian EMS model in rats. Ectopic lesions can be observed 1 week after surgery. The success rate of modeling increases with modeling time, stabilizing at 3 weeks postoperatively. Ki67, PCNA, and N-cadherin were significantly expressed in the uterus and ectopic foci tissues, and their expression levels increased with modeling time, while E-cadherin expression in the uterus and ectopic foci tissues decreased with modeling time. These Results showed good modeling success of the EMS rat model, suggesting that it could be used as a stable EMS modeling method.