Objective To investigate the relationship between fibrosis and M2 macrophages in endometriosis. Methods BALB/c mice model of endometriosis was established by intraperitoneal injection. The growth of ectopic lesions in mice was observed on the 7th,14th and 21th day after modeling. Masson staining was used to observe the degree of fibrosis and immunohistochemical method to detect the expression of CD206 and CD68 of mice. Image-Pro-Plus 6.0 was used for semi quantitative analysis of staining and the correlation between the degree of fibrosis and the expression of M2 macrophages was explored. Results The success rate of the establishment of endometriosis model by intraperitoneal injection was 100%. There was a positive correlation between fibrosis and the expression of M2 macrophages in endometriosis mice model. Conclusions The mice model of endometriosis can be established successfully by intraperitoneal injection and M2macrophages may promote fibrosis in endometriosis.