Miaoershan uranium ore field is one of the five large-scale uranium ore fields in center South China, in which includes the Chanziping uranium ore deposit, the largest scale carbonaceous-siliceous-pelitic rock type uranium ore deposit in china, and some granite-hosted uranium ore deposits. Pitchblende is ideal sample to date uranium mineralization directly. Meanwhile, it is also good mineral for U-Pb isotope measurements. U-Pb isotope measurements of pitchblende samples from the Shazijiang uranium ore deposit in northern Guangxi of China, indicated that there existed two mineralization stages, 104.4Ma and 53.0±6.4Ma, respectively. Combined with the major mineralization age of 74.1±9.9Ma for the Chanziping uranium ore deposit, three major mineralization stages were investigated for the Miaoershan uranium ore field with 104.4Ma, 74.1±9.9Ma and 53.0±6.4Ma. High initial Pb isotope ratio obtained by pitchblende U-Pb isochron method for the Shazijiang uranium ore deposit suggested that pre-mineralization had already occurred before this major mineralization stage. Three major mineralization stages were consistent with epochs of lithospheric extension in South China as indicated by mafic dikes geochronology, implying that uranium mineralization was constrained by the geodynamic setting of lithospheric extension.