The Bainaimiao deposit, located in the southeast margin of the Central Asian Orogenic Belt, is a large copper- gold deposit. The ore body, which consists of two ore belts, is mainly hosted in the granodioriteporphyry and the Bainaimiao Formation greenschist. The geochemistry compositions, zircon U- Pb ages and trace element compositions of the ore- bearing granodiorite porphyries from the south and north ore belts are analyzed in this study. The trace element geochemistry of the granodiorite porphyry from both ore belts are characterized by significantly enriched large ion lithophile elements (LILEs, e. g. , U, K, La.), depleted of high field strength elements (HFSEs, e. g. , Nb, Ta, Ti.), and the chondrite normalized REE patterns of the granodiorite porphyry show obvious characteristics of light rare earth enrichment. Compared to the granodiorite porphyry in the south ore belt, the granodiorite porphyry in the north ore belt is more depleted in Ba, Sr and P, indicating that the granodiorite porphyry in the north ore belt experienced a greater degree of fractionation and crystallization process than the granodiorite porphyry in the south ore belt. These geochemical features, combined with the Precambrian basement in this region, indicate that the ore- bearing granodiorite porphyry at Bainaimiao was formed in a continental arc. The ore- bearing granodiorite porphyry at Bainaimiao shows a low Mg # (0.37~0.49), low Nb/U (15.4~58.7) and high Th/Ta (1. 2~4. 63) values, suggesting that the magma had been contaminated by the continental crust during magma emplacement. The zircon trace elements of ore- bearing granodiorite porphyry from both belts exhibit significant enrichment of heavy rare earths, with LREE/HREE average values of 0.068 and 0.064, respectively, as well as moderate Eu negative anomalies (the average values of δ Eu are 0.81 and 0.64 respectively) and strong Ce positive anomalies (the averages of Ce 4+/Ce 3+ are 31 and 181 respectively). Their average zircon crystallization temperatures are 807 ℃ and 729 ℃, respectively. The granodiorite porphyry in the north ore belt has higher oxygen fugacity and is closer to the porphyry mineralization center than the granodiorite porphyry in the south ore belt, indicating that it is the productive porphyry of the Bainaimiao deposit, while the granodiorite porphyry in the south ore belt is the ore- bearing porphyry. The Concorde ages of granodiorite porphyry in the south and north ore belts are 437.3±2.9 Ma and 444.8 ± 3.4 Ma, respectively, which are consistent with the predecessors’ Re- Os ages of 438Ma and 445Ma, indicating that the porphyry mineralization at Bainaimiao is 445~438 Ma. The overlapping mineralization is after the transformation of regional metamorphism and was characterized by a large number of undeformed quartz- sulfide vein ores. The Bainaimiao Cu- Au deposit is a porphyry- overprinted type deposit.