The petrogenesis and genetic link to polymetallic mineralization of the granites in the Dayishan complex, southern Hunan province remain debated. Here, we present an integrated study on the petrology, zircon U-Pb ages and whole-rock geochemistry for this complex. Our findings indicate that the southern complex consists of (amphibole-bearing) biotite granites and muscovite granites emplaced at 153–151 Ma, and the central and northern complex consists of two-mica granites and tourmaline-bearing muscovite granites, respectively with the former emplaced at 164 Ma and the latter at 150 Ma. The (amphibole-bearing) biotite granites have SiO2 contents of 68.0–73.8 wt% and are enriched in alkalis and rare earth elements and depleted in Sr and Ba. They display Zr + Y + Ce + Nb > 350 ppm and 10000 × Ga/Al > 2.6 along with high zircon saturation temperatures (821–883oC). The two-mica granites and (tourmaline-bearing) muscovite granites have high SiO2 (74.4–77.3 wt%) and low Ga/Al, Zr + Nb + Ce + Y, K/Rb, Zr/Hf, and Nb/Ta along with low zircon saturation temperatures (709–817oC). Geochemical characteristics suggest that the (amphibole-bearing) biotite granites are A-type granites generated through shallow dehydration melting of early Paleozoic granitoids, and that the two-mica granites and (tourmaline-bearing) muscovite granites are fractionated A-type granites produced through fractionation crystallization from the (amphibole-bearing) biotite granites accompanied by fluid fractionation.