【Abstract】Objective To investigate the mechanism of follicular dysplasia and decreased endometrial receptivity of PCOS by studying the expression of BMP-15 in ovarian tissue and GdA in endometrium of PCOS model rats. Methods 21 days old SD rats were randomly divided into control group (25 rats) and PCOS model group（50 rats, were constructed with DHE）. Immunohistochemical staining was used to observe the expression of BMP-15 and FSHR in the ovarian tissue of the control group and the PCOS model group, as well as the expression of GD-A and LIF in the endometrium at different conception time. Results The expression of BMP-15 and FSHR in ovarian tissue of model group was significantly lower than that of control group, and the difference was statistically significant (P＜0.01). The positive expression of LIF and Gd-A in endometrium of normal rats gradually increased with prolongation of pregnant time, and the levels of GdA and LIF in the uterine flushing also has the same result. But at the same time the positive expression GdA and LIF in endometrium and the levels of Gd-A and LIF in the uterine flushing of model rats were statistically lower than that of normal rats at the same time, and no obviously changing with the increase of pregnant time. Conclusion Decreased expression of BMP-15 in ovary was related to the follicular dysplasia of PCOS, and the abnormal synthesis of Gd-A was one of reasons of decreased endometrial receptivity of PCOS.