Objectives To explore the associations of environmental endocrine disruptors on precocious puberty in girls. Methods This was a case-control study in which 30 girls with precocious puberty and 46 age- and race-matched prepubertal females were enrolled. The concentrations of 10 environment endocrine disruptors (bisphenol A, bisphenol B, butylparaben, propylparaben, ethvlparaben, methylparaben, mono-butyl phthalate, mono-2-ethylhexyl phthalate, monoethyl phthalate, and monomethyl phthalate) in urine and 10 steroid hormones (dihydrotestosterone, corticosterone, hydrocortisone, 11-deoxycortisol, 17α-hydroxy progesterone, 4-androstene-3,17-dione, estrone, deoxycorticosterone, pregnenolone, and dehydroepiandrosterone) in serum were detected with the liquid chromatography-mass spectrometry (LC-MS). Results According to the Mann–Whitney U test, urinary levels of bisphenol A, monobutyl phthalate, and monomethyl phthalate were significantly higher in the precocious group than in the prepubertal group, and blood levels of hydrocortisone, 11-deoxycortisol, corticosterone, deoxycorticosterone, and pregnenolone were significantly lower in the precocious group than in the prepubertal group (p<0.05, VIP>1). Conclusions Our findings confirm the association between phthalate exposure and the incidence of precocious puberty in girls. Control and reduction of children exposure to phthalate esters should be considered as a health priority.