Abstract: OBJECTIVE To explore the effect and working mechanism of Bushen Cupailuan Decotion on ovarian granulosa cells aromatase of polycystic ovary syndrome (PCOS) model rats. METHODS Bushen Cupailuan Decotion was taken by PCOS model rats which were induced by dehydroepiandrosterone (DHEA). RT-PCR and immunohistochemical methods were used to detect the mRNA and protein expression of granulosa cell aromatase in PCOS model rats. RESULTS Bushen Cupailuan Decotion significantly improved the mRNA and protein expression of granulosa cell aromatase in PCOS model rats (P<0.05). CONCLUSION Bushen Cupailuan Decotion can improve the expression of ovarian granulosa cell aromatase in PCOS model rats， which could be one of the mechanism of Bushen Cupailuan Decotion on promoting follicular development and releasing.