Yechangping super-large porphyry-skarn type Mo-W deposit,located in the East Qinling Mo polymetallic metallogenic belt,preserves crucial information on skarn formation evolution and mineralization.Through detailed field geological surveys and microscopic identification,magnetite in Yechangping Mo-W Deposit is classified into 3 types:Mt1 magnetite,formed during the late skarn stage,clay minerals,etc.;Mt2 magnetite,formed during the oxide stage,is semi-euhedral to euhedral and associated with garnet,tremolite,actinolite,etc.;and Mt3 magnetite,densely disseminated and associated with molybdenite or occurring in quartz polymetallic sulfide veins.Electron probe and LA-ICP-MS in-situ trace element analysis show that the average FeO content increases progressively from Mt1 to Mt3 magnetite.Mt1 magnetite is rich in elements such as Si,Mg,and Na,and has the highest content of V,Cr,Ti,Al,and Mo.Ti content in Mt2 magnetite decreases significantly,with a slight reduction in Si content and the highest levels of Mg and Mn.Mt3 magnetite has the lowest content of Ti,Si,Na,and Ca.The changes in magnetite element characteristics suggest that Fe is easily replaced by Si,Ca,and Al elements,with Mo and other ore-forming elements gradually enriching in the ore-forming fluids during magnetite crystallization.Genesis discrimination diagrams of magnetite indicate that Mt1 magnetite has a different source material compared to Mt2 and Mt3,tending more toward a magmatic-hydrothermal origin,while Mt2 and Mt3 are more metamorphic hydrothermal in nature.The host wall rock participated more in the mineralization with the formation of Mt2 magnetite.From the higher temperature early Mt1 magnetite to the lower temperature late Mt3 magnetite,V and Ti show a clear positive correlation.Discrimination diagrams for fluid-rock interaction indicate that metasomatism intensifies progressively.Therefore,changes in oxygen fugacity and the increasing degree of fluid-rock interaction in Yechangping Mo-W Deposit are the main factors controlling mineralization.