Abstract: Xilaokou gold deposit is a large-scale gold deposit in the northeast margin of Jiaolai Basin, which has made breakthrough in deep prospecting in recent years.The gold orebodies mainly occured in the structural fracture zone between the Paleoproterozoic Muniushan monzogranite and the Mesozoic Queshan mylonitized granite.Lamprophyres in the area are closely related to gold deposits in time and space.In order to explore the formation age and genetic mechanism, we carried out petrography, geochemistry and zircon U-Pb age research.The geochemical results show that lamprophyres are enriched in alkali, potassium, large ion lithophile elements and light rare earth elements, but depleted in titanium, high field strength elements and heavy rare earth elements.The Nb/Ta and Zr/Hf ratios are far higher than the value of continental crust, and close with the primitive mantle, which proves that the magma source is mainly mantle and is not strongly contaminated by the crust. Zircon U-Pb chronology shows that the formation age of intramineral dykes is 118.6±1.5 Ma, and the formation age of premineral dykes is 157±4~150.2±2.8 Ma. Except for the above young zircons, the rest are captured old zircons.The isotopic age of old zircons recorded the magmatic and metamorphic events of Neoarchean, Paleoproterozoic, Neoproterozoic and Triassic, which is consistent with the records of Paleoproterozoic magmatic intrusion, Mesoproterozoic crustal extension and metamorphism and Triassic plate collision events. The results of drills sampling show that the lamprophyres and the gold veins share the same structural channel. Although the gold content is generally not high, its "fading" effect really provides some ore-forming materials.It has been confirmed that the lamprophyre original magma has low gold content and poor gold carrying capacity, but it still plays an important role of "chemical barrier" in the process of mineralization.