Objective To explore the effect of Bushencupailuan decoction, a Chinese medicine formula, on polycystic ovary syndrome (PCOS) and its mechanism through observing the sex hormones, anti-Müllerian hormone (AMH) and the morphology of ovaries of PCOS rat models. Methods Bushencupailuan decoction was administered in DHEA-induced PCOS model rats. The pathology of ovaries was examined, and the serum sex hormones and AMH were detected. Results Compared with the normal group, the ovaries of model group rats had severe diffuse cystic dilatation and cystic cavities of different sizes. The granular layer cells were compressed into flat or cubical shapes. Corpora lutea and follicles in various stages of development were rare. Bushencupailuan decoction obviously improved the numbers of mature follicles and corpora lutea, levels of sex hormones and AMH of PCOS model rats compared with those of model rats (P<0.05). Conclusions Bushencupailuan decoction can treat PCOS by improving the serum sex hormone levels in PCOS model rats, reduce serum AMH and help to restore ovulation.