To study the effect of dienogest for treating women with endometriosis, and to analyze its influence on ovarian function of the women. Methods: 65 women with endometriosis were selected and were divided into two groups according to the random number table from October 2020 to October 2021. 32 women in the control group were treated with subcutaneous injection of leuprorelin acetate microspheres, and 33 women in the observation group were treated with oral dienogest tablets combined with subcutaneous injection of leuprorelin acetate microspheres. The curative effect, the score of Visual Analogue Scale (VAS), the levels of serum indicators, such as carbohydrate antigens 125 (CA125), matrix metalloproteinase-2 (MMP-2), galectin-3 (Gal-3), and vascular endothelial growth factor (VEGF), the ovarian reserve function indicators such as anti-Mullerian hormone (AMH) level, and antral follicle count (AFC) number, and the adverse reactions rate of the women were compared between the two groups. Results: There was no significant difference in the total effective rate (84.9% vs. 81.3%) of the women after treatment between the two groups. The scores of dysmenorrhea, and the degrees of non-menstrual abdominal pain and pain during intercourse of the women in both groups after treatment had decreased significantly (P<0.05), but the changes of which had no significant difference between the two groups (P>0.05). The levels of serum CA125, MMP-2, Gal-3, and VEGF of the women in both groups after treatment had decreased significantly (P<0.05), but the AMH level and AFC number of the women in both groups after treatment had no changed significantly (P>0.05), and the changes of which had no significant differences between the two groups (P>0.05). The incidence of perimenopausal symptoms (0) of the women in the observation group was significantly lower than that (21.9%) of the women in the control group (P<0.05). Conclusion: The effect of dienogest for treating the women with endometriosis is good, and which does not damage the ovarian function of these women with less side effects.