Objectives: To investigate the correlation between serum vitamin D level and idiopathic central precocious puberty (ICPP) in girls, in order to provide basis for the clinical prophylaxis and treatment. Methods: The clinical data of 92 girls with ICPP as the observation group and 85 healthy girls as the control group in our hospital from February 2017 to August 2018 were recorded. Their serum FT3, FT4, TSH, PRL, LH, FSH, peak of LH, peak of FSH, E2 and 25-OHD levels were detected. Results: The serum vitamin D levels in girls with ICPP were obviously lower than those in healthy girls, which had statistically significant difference (P<0.001). BA, BA/CA, MBI SDS, uterine volume, ovarian volume and maximum follicular diameter had no significant difference between patients with vitamin D deficiency and those not in the observation group (P>0.05). However, breast development had significant difference between the 2 groups (P<0.05). In addition, difference in TSH, PRL, LH, FSH, LH surge and FSH peak were not significant between patients with vitamin D deficiency and those with normal vitamin D (P>0.05), but the serum E2 levels had significant difference between the two groups (P<0.05). Conclusion: Lack of serum vitamin D and breast development age in ICPP girls are closely related, which perhaps relates to the serum E2 levels.