This paper provided LA-ICP-MS zircon U-Pb age,petrographic and geochemical characteristics of the monzogranite in Yili area,northern Great Hinggan Mountains,and discussed the formation age,genesis and geological significance of the rocks.Methods:Based on the field work, through the microscope observation,the whole rock chemical analysis and the LA-ICP-MS zircon U-Pb dating of monzogranite in Yili area.Results: Zircons from two representative intrusive rocks are euhedral—subhedral in shape and display oscillatory growth zoning in CL images,implying their magmatic origin.The dating results indicate that the monzogranites formed in the Early Jurassic during the age of 175.8~174.5 Ma,suggesting the Early Jurassic in age.The granites are characterized by high silicon (SiO2=71.23%~74.52%), high alkali and potassium (Na2O+K2O=6.31%~8.31%,K2O=2.58%~4.78%),low magnesium (MgO=0.43%~1.50%),low calcium (CaO=0.91%~1.81%),and A/CNK ratios ranging from 0.97 to 1.16.The granites are generally enriched in large ion lithophile elements (LILEs),such as Rb,K,Th,and relatively depleted in heavy rare earth elements (HREEs) and high field strength elements (HFSEs),such as Nb,Ta,P,Ti,with (La/Yb)N ratios of 14.07~50.34.No obvious negative Eu anomalies (δEu=0.88~1.71) have been identified.Zircon saturation temperatures (714~745℃) are significantly lower than Cretaceous A-type granites (＞800℃).Conclusions: Collectively,it is suggested that these granites belong to quasi aluminum-weak peraluminous and high-K calc-alkaline I-type ones.The petrological and geochemical features indicate that their primary magmas are derived from partial melting of the juvenile lower crust.Considering the background of regional tectonic evolution,it is suggested that the Early Jurassic monzonite granite from the Yili area formed in an active continental margin setting related to the southward subduction of the Mongol—Okhotsk oceanic plate.