Abstract: The Chaganhadayinhengga strongly peraluminous granites in East Ujimqin Banner of Inner Mongolia are located in the Xing-Meng fold belt along the central and eastern section of Central Asia-Mongolia orogenic belt between the North China plate and the Siberia plate. The main rock type is garnet-bearing two-mica monzonitic granite. Based on zircon U-Pb isotopic dating, geochemical analysis and tectonic environment discrimination in combination with regional correlation, the authors have reached the following conclusions:The source area of the Chaganhadayinhengga rock mass might have been related to the partial melting of meta-morphosed mudstone; during Late Paleozoic period, before the formation of strong peraluminous granite, even Erlian-East Ujimqin Banner area underwent collisional orogeny, and then after collision, the evolution entered into the post orogenic extension-expan-sionl period. Studies show that the Chaganhadayinhengga rock mass belongs to the Carboniferous-Early Permian typical post colli-sional high temperature type peraluminous granites rarely reported by previous researchers.