Objective To analyze the correlation between vitamin D,body mass index(BMI)and sex hormone levels in girls with idiopathic central precocious puberty(ICPP).Methods The clinical data of 100 girls with ICPP who were treated in the Children′s Hospital Affiliated to Capital Institute of Pediatrics from January 2019 to January 2021 were retrospectively analyzed,and they were set as the ICPP group,and 80 girls with normal development during the same period were selected as the control group.The changes of vitamin D level,BMI,gonadotropin and sex hormone levels in the ICPP group before and after treatment were compared with those in the control group,and the relationship between vitamin D level and BMI and sex hormone levels was analyzed.Results The levels of 25-hydroxyvitamin D3[25(OH)D3]in the ICPP group before treatment were lower than those in the control group,BMI,body mass index standard deviation score(BMI SDS),luteinizing hormone(LH),the levels of follicle-generating hormone(FSH)and estradiol(E2)were higher than those in the control group,and the differences were statistically significant(P<0.05).There was no significant difference in BMI SDS,FSH and E2 between the ICPP group and the control group after treatment(P>0.05).The levels of 25(OH)D3 and LH in the ICPP group after treatment were lower than those in the control group,and the BMI was higher than that in the control group,and the differences were statistically significant(P<0.05).The level of 25(OH)D3 in the ICPP group after treatment was higher than that before treatment,the levels of BMI SDS,LH,FSH and E2 were lower than those before treatment in ICPP group,and the differences were statistically significant(P<0.05).In ICPP group,25(OH)D3 in ICPP girls before treatment was negatively correlated with BMI,BMI SDS,LH,FSH,E2 levels(P<0.05).Conclusion ICPP girls generally have vitamin D deficiency,which is closely related to the increase of BMI and the increase of sex hormone levels.