Objective To analyse the imaging features of the girls with idiopathic central precocious puberty (ICPP) and premature thelarche (PT),and to explore the role of the magnetic resonance imaging (MRI) in the differential diagnosis.Methods A total of 35 girls with ICPP and 35 PT girls which from a provincial hospital in Henan were selected as observed objects,all the children had MRI scans of the cranial saddle area and the pituitary height were measured,and the developmental level of the pituitary gland was divided by Elster law. Results The mean value of pituitary height of ICPP group was (5.18±1.01) mm and (4.30±0.38) mm of the PT group,there was a statistically significant difference between the two groups (P<0.05);The Elster's grade of pituitary morphology which was equal or greater than IV grade of ICPP group and the PT group were accounted for 82.86% and 11.43% respectively (P<0.05).Conclusion s The pituitary height in ICPP group is higher,the upper edge of the pituitary Morphology is full;The pituitary height in PT group is lower,the upper edge of the pituitary Morphology is mainly flat or low-lying.The examination of the pituitary by MRI is non-invasive and painless,and has important reference value in the differential diagnosis between ICPP and PT,and it can be used as the auxiliary examination of the precocious puberty.