Objective,2,To evaluate the effect of emodin on ovarian function and sex hormone level in rats with polycystic ovary syndrome.,Methods,2,Twenty-eight non-pregnant female Sprague Dawley rats with periodic regularity were randomly divided into four groups（7 rats/group），including control group，control+emodin group，polycystic ovary syndrome（PCOS）model group and model+emodin treatment group.PCOS model group and model+emodin group were injected with 4 mg estradiol valerate into the back muscle of rats to prepare PCOS model.After induction，rats in control+emodin group and model+emodin group were injected with emodin 25 mg/kg intraperitoneally.Rats in control group and PCOS model group were injected with the same amount of normal saline.All these groups were treated once a day for 14 days.The body weight of rats in each group was measured every week.After 14 days of treatment，peripheral blood was collected from tail vein of rats in each group，and serum was obtained by centrifugal separation for the related tests.After the rats in each group were killed by decapitation，samples of uterus and ovary tissues were collected，and the weights of ovaries and uterus were measured respectively.The sexual cycle of rats was measured，the ovarian mass/body mass and uterine mass/body mass were calculated，the histological changes of ovaries and uterus were observed by HE staining，and the levels of testosterone and anti Mullerian hormone（AMH）in plasma were measured.,Results,2,Compared with the blank control group，the estrus interval of the control+emodin group had no significant change（,P,>,0.05）.Compared with the blank control group，the proportion of estrus interval in PCOS model group was higher（,P,<,0.05）.Compared with PCOS model group，the proportion of estrus interval in model+emodin group was lower（,P,<,0.05）.Compared with the blank control group， the ovarian mass/body mass of rats in the control+emodin group had no significant change（,P,>,0.05）.Compared with the blank control group，the ovarian mass/body mass of PCOS model group was higher（,P,<,0.05）.Compared with PCOS model group，the ovarian mass/body mass of model+emodin group was lower（,P,<,0.05）.Compared with the blank control group，the uterine mass/body mass of rats in the control+emodin group had no significant change（,P,>,0.05）.Compared with the blank control group，the uterine mass/body mass of PCOS model group was lower（,P,<,0.05）.Compared with PCOS model group，the uterine mass/body mass of model+emodin group was higher（,P,<,0.05）.In PCOS group，a large fluid-filled cystic follicle appeared，its granular layer died off，and its membranous layer formed the inner wall of epithelial-like cell proliferation，and the cystic fluid contained macrophages.This phenomenon was not observed in the model+emodin group，and the tendency of follicle enlargement was not observed.Compared with the blank control group，the serum androgen level in PCOS model group was higher（,P,<,0.05）.Compared with PCOS model group，serum androgen level in model+emodin group was lower（,P,<,0.05）.Compared with the blank control group，the serum AMH level in PCOS model group was higher（,P,<,0.05）.Compared with PCOS model group，AMH level in model+emodin group was lower（,P,<,0.05）.,Conclusion,2,Emodin can improve the ovarian function of PCOS rats and keep the balance of the levels of various sex hormones.