The Lala Fe-Cu-REE deposit, reported as a typical IOCG deposit in the Kangdian region, is located at the western margin of Yangtze Block. Fluorite is one of the most important gangue minerals in the Lala IOCG deposit, which is intergrown with chalcopyrite and molybdnite, and recorded important information about the source and evolution of the ore-forming fluid. Trace elements geochemistry of fluorite and its implications for source of ore-forming fluid are discussed through content, ratio and spider diagram of trace elements. Two stages of fluorite with three generations are identified in the Lala IOCG deposit. Fluorite (I) and fluorite (II) belongs to metamorphic metallization stage. Fluorite (I) is intergrown with flaky molybdenite (I), and are isolated cube shaped. Fluorite (II) is intergrown with banded molybdenite (II) in the vein or massive-disseminated ores, light purple. Fluorite (III) belongs to hydrothermal mineralization stage, intergrown with chalcopyrite and calcite veins, which cut the ores with fluorite (I) and fluorite (II), with a cubic habit. It turned out that: the content of trace elements is variable in fluorite (I) and fluorite (II) while it is stable in fluorite (III), which is dominated by its content in the original fluid and the nature themselves. The results suggested that: ①Fluorite (I) and fluorite (II) are homogenous products at different generations, seawater phase ore-forming fluids derived from the host rock, characterized by high content of F , Cu, Mo, Y and low pH, and exhumation might migrated at small scale.②Fluorite (III) has a different source from fluorite (I) and fluorite (II). Infiltration and leaching host rock by meteoric water or groundwater formed its freshwater phase ore-forming fluids, which is characterized by high pH and low content of F^-, and exhumation might infiltration flew or migrated at a long distance.