Since the formation of different granitic rocks involves their material sources and forming mechanism and reflect different kinds of minerallization, it is. necessary to first determine the genetic type of the granite when studing the mineral deposits related to it. In South China, the granites are mainly transformed and syntectic granitic rocks. Three late Yanshanian granite masses exposed in Wubu lead-zinc ore dis· trict are all ultra-hypabyssal subvolcanic rocks. According to their geological,petrological, mineralogical, petrochemical characters, trace-element distribution,and formation temperature, they are considered to belong to syntectic granites. After analysing large amounts of data of the circum Pacific area (including Wubu and Nanjing-Wuhu districts)，it is found that the lead isotopic composition, of granitic rocks may reflect the evolution of the geospheres and represent diff- event sources of materials. Therefore, the author suggests that lead isotopic composition may be used as new markers for distinguishing the genetic type of granites. With the change from mantle-derived granite to syntectic and then totransformed-type granite, the mantle material in granite decreases, while that from the crust gradually increases together with the content of radiogenic lead.