Objective To explore the pathogeny and clinical features in 231 preschool girls with isosexual precocious pubertyin in Kunming. Methods Gonadotropin releasing hormone (GnRH) stimulate experiments were applied to determine the luteinizing hormone (LH), and follicle stimulating hormone (FSH), estradiol (E2) level, thyroid function, the function of liver and kidney were also measured. The tumor markers, pelvic B ultrasound, bone age and pituitary MRI were determined in the girls with ovarian tumor. Results There were 152 cases with peripheral precocious puberty (PPP, 65.8%), and 82 of them could reach the definite etiological diagnosis. The causes of 60 cases were ingestion of drug and tonic accidentally (acyeterion in 55 cases), 20 cases were ovarian tumor, 2 cases were McCune-Albright syndrome, and etiology was unknown in 70 cases. 57 cases were part precocious puberty (24.7%), including 53 cases with simple premature thelarche, 4 cases with premature pubarche. During 22 cases of central precocious puberty (CPP, 9.5%), there were 15 patients with idiopathic central precocious puberty,3 cases with pituitary micro adenoma,2 cases with hypothalamic hamartoma, 1 case with hydrocephalus, and 1 case with hypothyroidism. Long term follow-up of 1~3 years found that 5 cases were peripheral precocious puberty, and partial sexual precocity were transformed into central precocious puberty in 5 cases. Conclusions Precocious puberty has different characteristics under different causes. Pathological change is the main cause of CPP (7/22, 30.82%), accompanied by elevation of sex hormone and advancement of bone age. PPP with unknown etiology and drug ingestion is the most common. Partial sexual precocity turned into central precocious puberty accounts for the highest proportion (5/57, 8.77%). Because pituitary MRI and pelvic ultrasound are not applied in the younger children, they need long-term follow-up. [ABSTRACT FROM AUTHOR]