The Zebuxia Pb—Zn deposit is located in the western of Gangdese porphyry Cu—Mo—Polymetallic metallogenic belt, Xizang(Tibet), which occurs lots of K- feldspar granite porphyry. In order to find out formation age and genetic types of the K- feldspar granite porphyry, further discuss diagenetic environment and the relationship with Pb—Zn mineralization ., Methods：Detailed geological survey，LA- MC- ICP- MS zircon U- Pb dating and the whole- rock geochemical analysis of K- feldspar granite porphyry.Results：Zircon U- Pb geochronology results show that the K- feldspar granite porphyry was formed in 14.18±0.15 Ma pertain to magmatic products of the Miocene. Major elements of the K- feldspar granite porphyries have characteristics of enrichment silica and alkali，depleted magnesium，A/CNK ranges from between 1.08 to 1.38. Rare earth elements have the right- leaning pattern of the LREE enrichment and medium negative Eu abnormality. Trace elements are rich in Rb，Th，U，K and Pb，but which are poor in Ba，Sr and HFSE, such as Nb，Ta，P and Ti. Conclusions：K- feldspar granite porphyries have the differentiation characteristics of S- type granite. The K- feldspar granite porphyry were probably formed in post- collision extensional setting background followed the Indian—Asian continental collision，and consistent with the epoch of the massive porphyry emplacement period and associated porphyry copper （molybdenum） mineralizatio of Gangdise metallogenic belt in the Miocene，namely they may have the same diagenesis and mineralization environment. In addition，it provides theoretical and practical basis for prospecting porphyry- related Pb—Zn deposits in the western part of the Gangdise metallogenic belt.