Objective To investigate the therapeutic effect of rehmanniae radix praeparata on female central precocious puberty (CPP) rats and elucidate its possible mechanism. Methods Forty-eight 28-day-old female SD rats were randomly divided into normal group, model group, positive control (leuprorelin 100 μg/kg) group, and low-, medium-, and high-dose rehmanniae radix praeparata (0.8, 1.6, 3.2 g/kg) groups, with 8 rats in each group. The CPP rat model was established by N-methyl-DL-aspartate (NMA) method, during the modeling period, the rats were treated with leuprorelin or different doses of rehmanniae radix praeparata, once a day until available. The time of vaginal opening and the first interestrus were recorded. HE staining was used to detect the endometrial thickness and the number of ovarian corpus luteum. The levels of luteinizing hormone (LH), follicle stimulating hormone (FSH) and estradiol (E2) in serum were detected by ELISA.The protein expression levels of gonadotropin-releasing hormone (GnRH), insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) and growth hormone (GH) in the hypothalamus of rats were detected by Western blot. Results Compared with normal group, the time of vaginal opening and first estrus interval in the model group was significantly shorter (all P<0.05). The thickness of the uterine wall and the number of the corpus luteum of the ovary were significantly increased, while the levels of LH, FSH and E2 in serum and the protein expression levels of GnRH, IGF-1, IGFBP-3 and GH in hypothalamus were significantly increased (all P<0.05). Compared with model group, the time of vaginal opening and first estrus interval in the positive control group and rehmanniae radix praeparata dose groups were significantly longer (all P<0.05). The thickness of the uterine wall and the number of the corpus luteum of the ovary were significantly decreased, while the levels of LH, FSH and E2 in serum and the protein expression levels of GnRH, IGF-1, IGFBP-3 and GH in hypothalamus were significantly decreased (all P<0.05). Conclusion Rehmanniae radix praeparata can reduce the growth hormone level in CPP rats and inhibit precocious puberty, the mechanism of which may be related to delaying hypothalamic-pituitary-IGF-1 axis activation