There are lots of granitoids exposed in Mudanjiang-Jixi area, represented by such rock bodies as Chaihe, Shichang，Guangfutun and Gangzigou，which were formerly regarded as Proterozoic granite bodies. With the single zircon stepwise evaporation-deposition method proposed by Kober, zircon samples collected from granite, granite porphyry migmatite and granitic veins in this area were dated isotopically, and the results indicate that the emplacement and migmatization of granitoids in this area mainly took place during the Variscan orogcny of 290-250 Ma，that some granite bodies were probably formed in Caledonian period of 488-409 Ma instead of in Proterozoic, and that the Precambrian metebasement might exist on both sides of the Bamiantong complex，as is evidenced by the age data of inherited zircon (2871士8 Ma and 1134士14 Ma) obtained in granite and migmatite.