Background The effects of dimethyl phthalate (DMP) on the reproductive system of mammal females are unclear because no studies have been conducted on this topic. Methods In this study, 40 C57 female mice were used as experimental subjects and evenly divided into 8 groups, which were fed with mixed DMP (0, 0.5, 1, and 2 g/kg bw/day) and corn oil. After 20 days and 40 days of gavage, the mice were weighed and their individual ovary organ coefficients measured. Results Changes were discovered on progesterone, estradiol, follicle-stimulating hormone and luteinizing hormone in mouse serum, and on the apoptosis rate of ovarian granulosa cells. Conclusions Prolonged exposure to DMP led to decreased secretion of FSH hormones and increased secretion of E2 and LH hormones. Furthermore, DMP interfered with the pituitary-ovary axis and increased the apoptosis rate of ovarian granulosa cells. Therefore, prolonged exposure to DMP is likely to have negative effects on reproduction and development.