The Gezan Copper Polymetallic Ore Concentration Area is one of the important Cu—Mo polymetallic mineralisation zones in the Southwest Sanjiang Tethys tectonic domain. A series of porphyry—skarn type Cu(Mo) polymetallic deposits were formed during the Yanshan period along with tectonic—magmatic—hydrothermal interaction. Among them, the Hongniu—Hongshan copper deposit is a representative deposit in the region. This paper carried out LA- ICP- MS zircon U- Pb dating, rock geochemistry and zircon Lu—Hf isotope analysis on the granite porphyry—quartz monzonite porphyry complex in Hongniu—Hongshan copper deposit based on systematic field work. The results show that the porphyry is Si- rich (SiO2=59.19%~72.20%) and alkali- rich (K2O+Na2O=6.65%~12.33%), has a high content of rare earth elements (ΣREE=163×10-6~588×10-6，average value is 272×10-6), a high fractionation degree of light and heavy rare earth elements (LREE/HREE=17.17~31.71), negative Eu anomaly (δEu=0.64~0.84), relatively enriched in large ion- loving elements such as Rb, Th, U and K (LILE), and relatively depleted in high field strength elements such as Nb, Ti, Ta and P (HFSE). The Hongniu—Hongshan copper deposit complex pluton is a set of quasi- aluminous—peraluminous high- potassium calc- alkaline- shoshonite series of highly differentiated I- type granites, which has the trend of evolving to A- type granites, with high strontium and low yttrium characteristics. The zircon LA- ICP- MS U- Pb ages of the three granitic porphyry samples are 80.11±0.63 Ma, 76.59±0.53 Ma and 76.49±0.63 Ma, respectively, and the zircon LA- ICP- MS U- Pb ages of the two quartz- monzonite porphyries are 77.27±0.70 Ma and 76.99±0.75 Ma. All belong to the Late Yanshanian. The zircon εHf(t) values range from -10.3 to -4.6, and TDM2 ages range from 1.277 to 1.582 Ga, with peak between 1.35 and 1.40 Ga, which indicates that the granite porphyry—quartz monzonite porphyry in Hongniu—Hongshan copper deposit originated from deep melting at the base of the Middle Proterozoic crust. Combined with previous studies, the formation of the granitic porphyry—quartz diorite in Hongniu—Hongshan copper deposit is closely related to the partial melting of the thickened crust of the Geza island arc formed in the early Indosinian period.