The whole rock and mineral Rb-Sr isotopic dating suggests that the Xinhuatun pluton located in Zhangguangcailing of Northeast China was emplaced in Middle Jurassic with isotopic ages of 160～165Ma, rather than belonging to Indosinian. Geochemical studies indicate that this pluton is of fractionated felsic I-type and experienced slight contamination by crustal material during its emplacement and crystallization. However, the major factor responsible for chemical variation seems to have been mineral fractionation. The young Nd model ages suggest a significant crustal growth in the period of Neoproterozoic-Phanerozoic.