Recent prospecting have revealed that lots of finegrained granitic dikes occurred in Gaoping area, South Zhuguang Mountains, and some of them are spatially related with U orebodies. Two groups of ages which including 252.9±1.9 Ma and 244±2 Ma have been detected though LA-ICP-MS U-Pb Dating of zircon, and suggested that the finegrained granites emplaced during Indonisian, with combination of U-Pb dating of uraninite. With consideration of regional uranium mineralization regularity in North Guangdong and regional uranium metallogenic features, this paper proposed that (1) during Indonisian, significant volumes of granites which could be divided into two stages that including coarsegrained (Early) and finegrained granites (Later) formed in South Zhuguang Mountains, and the later one mainly emplaced along regional faults; (2) during Yanshanian, mafic dikes emplaced along faults; (3) the location that later mafic dikes superimposed on earlier granitic dikes are the favorable space for later uranium mineralization.