Abstract: Gaoqiaogou granite porphyry is a part of Hannan Complex, which is located in the northern margin of the Yangtze plate. LA−MCP−MS U−Pb dating of Zircon indicates that the Zircon was formed at (794.4±5.7) Ma in the early South China epoch. The Rock Geochemistry is characterized by high silicon (75.78%～76.51%) , high alkali (K₂O＋Na₂O=7.78%～7.84%) , high potassium (K₂O/Na₂O=1.07～1.10) , high potassium calcium alkaline series, total rare earth elements ∑REE=272.57×10^–6, and obvious fractionation between light and heavy rare earth elements. The monzonitic granite porphyry was formed in the middle and late stage of magmatic evolution. The material of partial melting sedimentary rock and volcanic rock in the process of magma intrusion. The Gaoqiaogou granite porphyry was formed in the post-orogenic tectonic environment and emplaced strongly.