OBJECTIVE：To study the improvement eff ects and its mech anism of Guiyuan decoction formula granules （GDFG） on model mice with decreased ovarian reserve （DOR）. METHODS ：Totally 42 female ICR mice whith with normal estrous cycle were randomly divided into control group ，model group ，estradiol valerate group （positive control ，0.15 mg/kg）and GDFG low-dose，medium-dose and high-dose groups （0.75，1.49，2.98 g/kg），with 7 mice in each group. Except for control group ，other groups were given cisplatin （3 mg/kg）intraperitoneally to establish DOR model. After modeling ，administration groups were given relevant medicine intragastrically；model group and control group were given normal saline intragastrically ，once a day ，for consecutive 4 weeks. After last administration ，ELISA assay was used to measure the serum levels of anti-Müllerian hormone （AMH）and follicle-stimulating hormone （FSH）in mice. Histopathological morphology of ovarian was observed by HE staining. Protein distribution of AMH receptor Ⅱ（AMHRⅡ）and Smad 4 in ovarian tissue were observed by immunohistochemistry. Protein expression of AMHR Ⅱ and Smad 4 were detected by Western blot assay. RESULTS ：Compared with control group ，theserum level of AMH ，the expression of AMHR Ⅱ and Smad 4 protein in ovarian tissue in model group were significantly decreased （P＜0.01），while the FSH level in serum was significantly increased （P＜0.01）；follicles were crumpled and lost nucleus ，ovarian interstitial were fibrosis ，luteum were loose ； AMHRⅡ and Smad 4 protein in ovarian tissue were mainly distributed in the follicle membrane and ovarian interstitial. Compared with model group ，the serum level of AMH ，the expression of AMHR Ⅱ and Smad 4 protein in ovarian tissue was increased significantly in GDFG groups （P＜0.01），while the serum level of FSH was decreased significantly （P＜0.05 or P＜0.01）；in ovarian tissue ，follicles at all levels could be found and follicle morphology was improved ，and no obvious nuclear loss and cumulus formation were found ；AMHRⅡ and Smad 4 protein were mainly distributed in the follicular nucleus （except for GDFG high-dose group) and the granular cell membrane （mainly distributed in the sinus follicles of GDFG medium-dose group ）；they were slightly distributed around the mature follicular nucleus or in corpus luteum. CONCLUSIONS ：GDFG can improve ovarian function of DOR model mice. The mechanism may be related with promoting serum level of AMH ，protein expression of AMHR Ⅱ and Smad 4，improving the distribution of AMHR Ⅱ and Smad 4 protein in ovarian granulosa cell membrane and follicular nucleus ， reducing FSH levels.