Abstract：The Baishaziling tin deposit is hosted in the Dayishan composite granite body. Two types of tin deposit, altered granite type and greisen vein type, are distinguished, and they occur in association with each other in space. The paper discusses the genesis and ore-forming processes of the deposit according to the geological setting and geological characteristics of the deposit and the results of isotope and inclusion analyses. Pb isotope study shows that ore-forming materials of tin were derived from the mixed source of mantle and crust. Hydrogen and oxygen isotope features indicate that ore-forming fluids were mainly boiling magmatic water. Coupling of altered granite-type and greisen vein-type tin ore veins and consistency of their fluid inclusion and sulfur and lead isotope features show that the combined effect of tectonism and magmatic evolution was the main controlling factor for mineralization. With temperatures of 180-425℃, a salinity of 1.40-11.22% and pressures of (67-537)×105 Pa, the Baishaziling tin deposit is a mesothermal-hypothermal deposit.