The Dewulu pluton is located between Xiahe-Hezuo fault and Lishishan-Weidangshan fault. The hose rock is predominantly composed of granodiorite with subordinate quartz diorite and quartz monzodiorite, and contains a large number of microgranular mafic enclaves (MMEs). Some Cu-Au deposits occur within the pluton and have been studied by many researchers; nevertheless, there are few researches on the pluton. LA-ICP-MS zircon U-Pb dating on the granodiorite of the Dewulu pluton yielded an age of 225.9±1.3 Ma, suggesting that the pluton was formed in the early period of late Triassic, and might have been related to the continental collision between the Yangtze and North China plates. Petrogeochemical studies show that host rocks are characterized by high K₂O and low Y and MgO, while the MMEs by low K₂O and high Y and MgO. Both host rocks and MMEs have similar features in trace element spider diagram and REE distribution pattern and obvious linear relationship on Al₂O₃/MgO-SiO₂/MgO diagram. These phenomena indicate that material exchange took place in these rocks, and quartz diorite, quartz monzodiorite and granodiorite were generated by the mixing of mafic and felsic magmas resulting from the strong crust-mantle interaction occurring in the extensional environment after the collision of the Yangtze and North China plates. MMEs may be the remnant of the parental mafic magma, and their geochemical characteristics show that they might have been derived from the mantle which was enriched in Au, Cu and other ore-forming elements. The Cu and Au enriched fluid was produced during the evolution of the mixed magma, and precipitated in the Dewulu pluton to form the hydrothermal Cu-Au deposits.