The Furong deposit, located in the southern Qitianling pluton, is a giant tin deposit. In this paper, we studied the geochronology using the in situ LA-ICP-MS U-Pb method and geochemistry of cassiterite occurred in the pluton and country rocks. The cassiterites from the pluton yielded an isochron age of 156.5±4.1 Ma. Fe contents of the cassiterites with typical zonal textures decrease from core to rim. These cassiterites have high contents of HFSE (e.g. Nb, Ta, Ti, Sc) and low values of (La/Lu)_N. The cassiterites from the country rocks yielded an isochron age of 153.6±1.4 Ma. Fe contents of these cassiterites are lower than those of the cassiterite from the pluton, which also show a decrease trend from core to rim. The cassiterites occurred in the country rocks show very low contents of HFSE and relative higher values of (La/Lu)_N (0.011-0.084) than those from the pluton. Our data indicate that zonal texture of cassiterites is related with the Fe content. Isomorphous substitutions of the cassiterites occurred mainly between Fe and Sn, which is accompanied by substitution of Nb, Ta, Sc, Ti and REE by Sn (especially in the cassiterites from the pluton). Highly-evolved magma with high-F contents interacted intensively with the Cambrian sedimentary rocks with high W, Sn and HFSE contents. Ore-forming fluid enriched in F, HFSE, HREE, Fe and Sn exsolved and precipitated within the pluton in early stage (156-159 Ma). And then, the ore-forming fluid transported to, and interacted with, the Devonian-Carboniferous carbonate strata, resulting in the formation of the cassiterites in the country rocks.