The Duobaoshan porphyry Cu-Mo deposit is an important Cu deposit in Northeast China. Systematic isotope dating was conducted to determine the metallogenic age of the deposit. The data show that the ore-forming process and the intrusion of the host rocks were completed in the early Ordovician. According to the ages of mineralization and intrusion of host rocks, the sedimentary setting of the Duobaoshan Formation and the geochemical characteristics of rocks hosting the deposit, the authors hold that the porphyry Cu-Mo deposit was formed in an island arc regime related to plate subduction in the Early Ordovician, and that the prospecting direction for such a type of porphyry copper deposits should be in the magma island arc belt distributed in Duobaoshan-Yi’ershi area.