【Objective】 To explore characteristic of premature thelarche and rate of central precocious puberty in these children. 【Methods】 162 infants and young children(1 month~3.4 years old) were given regular physical examination and follow-up from July of 2007 to August of 2010. Children who were with breast nodus disappear and reproductive, more than 2 years old and 2.5 cm of breast size were received examinations of abdomen and breast ultrasonography, sex hormone and bone age, some of them were taken into GnRH provocation test. 【Results】 Rate of breast nodus disappearance before 2.5 years old was 91.98%, majority of breast nodus was appear before 2 years old and frequently seen in 5 to 8 months infants. The most feeding pattern was breast feeding and breast-cow's milk mixed feeding was more than cow's milk feeding in premature thelarche infants and young children. Breast size, number of breast nodus reproductive and bilateral breast nodus appeared were no significant difference in different feeding ways. Results of ultrasonography were mammillary nucleus developed, uterus undeveloped and normal adrenal gland. All children were not accelerated linear growth and occur other sexual characteristics in follow-up period. Rate of abnormal in ovary, sex hormone and bone age was 2.47%, these abnormal children were negative in GnRH provocation test, they could not diagnose central precocious puberty. 【Conclusion】 Premature thelarche in infants and young children is generally benign conditions, but they should be followed-up for finding out CPP in time.