Objective To study the early diagnostic predictors and key follow-up parameters for girls with rapidly progressive central precocious puberty (RP-CPP). Methods A total of 260 girls with CPP participated in a prospective, nonrandomized, multi-center, nested case control study. After follow-up six months without any therapy, 114 girls were divided into RP-CPP (n=70) and slowly progressive CPP (SP-CPP) (n=44) groups. Results The basal serum LH and insulin-like growth factor Ⅰstandard deviation score (IGF-ⅠSDS) were the important risk factors of RP-CPP (OR 4.04, 1.578), especially the former. The receiver operating characteristic (ROC) curve revealed that the areas under the ROC curve of basal LH and IGF-ⅠSDS were 0.83 and 0.807, respectively. The levels of basal LH and IGF-ⅠSDS were at 0.52 mIU/ml and 0.35 respectively for the accuracy diagnosis of RP-CPP with the maximum Youden indexs. After follow-up for six months, the change levels of height, breast stages, bone age/chronological age ratio, serum LH, uterine and ovarian volume in RP-CPP group were significantly higher than those in SP-CPP group (all P<0.05). Conclusions The level of basal serum LH and IGF-ⅠSDS may be used as the risk predictors for early diagnosis for girls with RP-CPP. The change levels of basal LH, progress rates of gonad and sex character, height, and impaired growth potential seem to be the key follow-up parameters for CPP progress.