Abstract: Zircon U-Pb dating, whole-rock elements and Sr-Nd isotopes, and mineral O isotope analyses were carried out for Neoproterozoic granites at Shiershan in South Anhui Province. Zircon U-Pb dating indicates two age phases of magmatic zircons formed at 777 ± 9 Ma and 827 ± 15 Ma, respectively. As a whole the granites are characterized by high SiO2 （74.7 - 78.5% ）, high K2O （3.99 - 5.64% ）, high K2O/Na2O ratios （ 1.5 - 3.0） and very low contents of mafic components ∑TiO2 ＋ Fe2O3^T ＋ MgO （ 1.2 - 3.0% ）, showing the features of highly evolved crust. They have similar REE patterns showing LREE-enrichment and strong negative Eu anomalies （Eu/Eu＊ = 0.2 -0.4）. The nearly neutral whole-rock εNd （t） values of- 0.53 to ＋0.72 indicate a magraatic source with significant proportions of depleted mantle component. The δ^180 values of zircon range from 2.4‰ to 7.1‰, indicating the granites at Shiershan are low δ^18O magmatic rocks; The big variation of δ^18O values reflects their genesis was related to supersolidus hydrothermal alteration. Compared with zircon, the other mineral separates yield considerable variation of δ^18O values, suggesting they suffered different degrees of hydrothermal alteration. On the basis of element and isotope results, we interpret the zircons of 827 ± 15 Ma as of the inherited one, and those of 777 ± 9 Ma as the coeval magmatic genesis. It is inferred that an extensive mantle-derived magmatic activity took place at ca. 1 100 to 880 Ma, and a juvenile crust was formed in the southeastern margin of the Yan- gtze craton. It is assumed that due to anomalous thermal pulse by a mantle superplume event at ca. 827 Ma that heated the overlying lithosphere, the igneous rocks were generated by remelting of the juvenile crust in the thickened orogenic crust. Accompanying rapid opening of the rift, mantle-derived magma moved upward at ea. 780 Ma along the rift zone, resulting in high-T meteorie-hydrothermal alteration within the rift teetonie zone in the level of middle-upper erust, and voluminous volcanic rocks were formed during this period. Due to different degrees of water-rock reaction at high temperature, altered wallrocks of magma chamber within the rifling zone have differently low δ^18O values. At ca. 800℃ the altered wallroeks began to be melted, and almost synchronously emplaced and cooled to form granites. Most old inherited zircons were resorbed, a great deal of magmatic zircons were crystallized at ca. 777 Ma. Because of a very short duration of the melt phase, the granitoid magma could not be uniformized, consequently the granites with differently low δ^18O values were generated. The granites at Shiershan suffered at least two phases of partial melting processes, thus they have the features of highly evolved crust characterized by high SiO2, high K20, and low contents of mafic component.