///This paper reports biotite and muscovite single-grain mineral Rb-Sr ages and geochemical results for the Weishan granite, a typical Mesozoic composite granitic pluton in South China that includes Xinpu highly-evolved granite, Tangshi biotite monzogranite and Xiangzikou two-mica granite, probing into multistage magmatisms and implications for the petrogenetic and metallogenic processes. The results show that: 1） biotite that crystallized at (227.0±13) Ma（MSWD=1.6） from the Xinpu highly-evolved granite is low in Al, Mg, Rb and ACNK ratios, but high in Fe and Fe/（Fe＋Mg） ratios; 2） biotite that crystallized at (221.9±5.8) Ma（MSWD=3.8） from the Weishan＇s main body, the Tangshi biotite monzogranite, is high in Mg and Sr, but low Fe/（Fe＋Mg） and Rb/Sr ratios; and 3） biotite from the Xiangzikou two-mica granite, formed at (210.1±3.3) Ma（MSWD=0.21） that were determined by single-grain muscovite Rb-Sr isochron age, is low Sr and high in Al, Rb, ACNK and Rb/Sr ratio; and 4） muscovite from the Tangshi biotite monzogranite is formed during the hydrothermal process, and is characterized by very low concentrations for most major and trace elements and high Fe/（Fe＋Mg）, Cs/Nb, Rb/Sr ratios, whereas muscovite from the Xiangzikou two-mica granite is formed by metasomatisms of biotite and K-feldspar etc., with higher Al, Ti and Na. Both of the Xinpu highly-evolved granite and the Xiangzikou two-mica granite are potential sources for uranium mineralization, but the latter shows a better perspective because of intense hydrothermal alternation.