Objective To study the relationship between estrogen receptor gene polymorphism of precocious girls and environmental endocrine disruptors, as well as, to clarify the molecular mechanisms of body's susceptibility to environmental endocrine disruptors differences. Methods The blood samples were collected from 123 cases of precocious girls and 102 cases of normal girls.The concentrations of 4-nonylphend (4-NP), dibutyl phthalate (DBP), DEHP and P, P-DDE in serum samples were measured by using high performance liquid chromatography(HPLC), the volume of the uterus and ovary, the bone density, the content of estradiol(E₂) were determined at the same time.The contents of 4-NP, DBP, DEHP and P, P-DDE in serum of precocious girls and the indices of the target organs were analyzed by using correlation.Further, estrogen receptor α (ERα ) and estrogen receptor β (ERβ) gene polymorphisms were analyzed by using PCR-RFLP between the precocious girls who can be detected 4-NP, DEHP, DBP and P, P'-DDE in serum and normal controls who can not be detected the above four kinds of EEDs respectively and the effect relationship between them were observed. Results In normal control group, 4-NP, DEHP, DBP and P, P'-DDE, were detected in blood serum for 58%, 37%, 31% and 38.4% respectively, whereas, in precocious girls group, the four kinds of EEDs respectively were detected in blood serum for 89.7%, 63.3%, 64.8% and 100%.The levels of 4-NP, DEHP, DBP and P, P'-DDE in serum in precocious girl group were notably increased than those in control group(P all<0.01).In precocious girls group, there was a positive correlations between the 4-NP in volume of uterus and the volume of ovary and the density of bone;P, P'-DDE and volume of uterus also showed a the positive correlation.Compared girls with precocious puberty who can be detected 4-NP, DEHP, DBP and P, P'-DDE in serum and normal controls who can not be detected the above four kinds of EEDs respectively, there were significant differences in genotype distribution for the XbaⅠand the RsaⅠ polymorphism.Compared Xx with wild-type xx, the susceptibility to 4-NP, DEHP, DBP and P, P'-DDE was respectively 2.52, 7.01, 6.21 and 2.63 fold.Compared RR with wild-type rr, the susceptibility to 4-NP, DEHP, DBP and P, P'-DDE was respectively 7.36, 9.61, 8.67 and 6.77 fold. Conclusion Precocious girls are contaminated more severely than normal girls.Different kinds of EEDs might have different influencing extents to the target organs.Children exposed to EEDs haven't necessarily occurred precocious.One reason may be different genotypes expressed in different individuals.Xx and RR are susceptible genotypes to EEDs.