Objective To study the relationship of endocrine disruptors (EDCs) with premature thelarche in the 0-3 years old baby girls. Methods A total of 60 infant girls diagnosed with premature thelarche were selected as the case group in Children's Hospital Affiliated to Chongqing Medical University between August 2013 and June 2014, and another 60 healthy girls were included into a control group. Their parents were asked to finish questionnaires and each participants underwent B ultrasonic examination. The serum samples were obtained from both groups by professional doctors to examine the levels of estradiol, follicle stimulation hormone, luteinizing hormone, bisphenol A and diethyl phthalate. Results There were no significant differences in the age, FSH or LH levels between the case group and the control group (P=0.745, 0.721 and 0.195, respectively); the level of E2 in the case group was significantly higher than that in the control group (P=0.017); bisphenol A and diethyl phthalate levels in the case group were significantly higher than those in the control group ([272.9±101.3] μg/L vs [21.8±18.4] μg/L, P=0.000; [0.8±0.3] mg/L vs [0.3±0.1] mg/L,P=0.000). There was a positive correlation between the bisphenol A and diethyl phthalate in the case group (r=0.061, P=0.002), but not in the control group(r=0.302,P=0.102). There was no significant correlation between the sex hormone and the two EDCs (bisphenol A or diethyl phthalate) (P>0.05). Conclusion Premature thelarche in the infant girls between 0 and 3 years old is associated with serum estrogen level, bisphenol A and ethyl phthalate levels, and there is no relationship between genetic factors and environmental factors.