Objective This study explores the effects of Bushen Qyushi formula on the endocrine system of rats with polycystic ovary syndrome (PCOS), aiming to provide experimental evidence for the effectiveness of this treatment method in the treatment of PCOS. Methods The SD female rats were intragastrically administered the letrozole solution (1 mg/kg) once a day for 21 consecutive days to establish the PCOS model. The 18 PCOS model rats were divided into the model group, the Bushen Qyushi group and the positive control group. Another 6 healthy rats were used as the blank group. The Bushen Qyushi group was intragastrically administered Bushen Qyushi formula medicinal liquid (19 g of raw drug/kg), the positive control group was intragastrically administered the Diane-35 medicinal liquid (0.42 mg/kg), and the blank group and the model group were intragastrically administered normal saline, once a day for 21 days. After the administration, the rats were fasted for 12 hours, their body weight was measured, and then they were sacrificed. The unilateral ovarian index and uterine index were calculated. The serum testosterone (T), luteinizing hormone (LH), insulin (INS), and estradiol (E2) contents were determined by ELISA. The ovarian tissue morphology was observed by HE staining. The expression level of insulin-like growth factor-1 (IGF-1) in the ovarian tissue was detected by immunohistochemistry. The mRNA expression levels of extracellular regulated protein kinases 1 and 2 (ERK1 and ERK2) in the ovarian tissue were detected by RT-qPCR. The levels of ERK1, ERK2, phosphorylated-ERK1 (p-ERK1) and phosphorylated-ERK2 (p-ERK2) were detected by Western Blot.Results Compared with the blank group, the ovarian index, uterine index and serum E2 level in the model group decreased, while the serum T, LH and INS levels increased, and the expression levels of ERK1, ERK2 mRNA, IGF-1, ERK1, ERK2, p-ERK1 and p-ERK2 proteins in the ovary in the model group increased (P < 0.05). Compared with the model group, the uterine index and serum E2 level in Bushen Qyushi group and the positive group increased, while the serum T, LH and INS levels decreased, and the expression levels of ERK1, ERK2 mRNA, IGF-1, ERK1, ERK2, p-ERK1 and p-ERK2 proteins in the ovary in Bushen Qyushi group and the positive group decreased (P<0.05).Conclusion Bushen Qyushi formula can improve the hormone disorder and 〖JP2〗reduce the damage of ovarian granulosa cells in PCOS rats， which may be related to the inhibition of ERK1/2 protein expression