The Neoproterozoic SP (strongly peraluminous) granites from northeastern Hunan are composed mainly of Changsanbei and Daweishan granites. They have high ASI (about 1. 24). They are enriched in LREE and show flat HREE and negative anomalies of Eu/Eu* (averaged 0. 51). Depletion in Ba, Nb, Ta, Ti, P and enrichment in K, Rb and Th of these rocks indicate that they are ascribed to S-type granites. The 207Pb/206Pb age of the Changsanbei granites obtained with the single-zircon evaporation technique is 929 + 6 Ma. They have relatively old Nd model ages and the age of inherited zircon is 2491 + 2 Ma, suggesting that there might exist a late Archean-early Proterozoic basement. The orogen, in which these granites are located, has signatures of the high-temperature collision orogen which are similar to those of the Lachlan fold belt. The CaO/Na2O ratio is higher than 0. 3, suggesting that they were probably derived from partial melting of the psammitic rocks in the Mesoproterozoic Lengjiaxi Group. The zonal distribution of all these Neoproterozoic SP granites in this and other areas along the Jiangnan orogen suggests that their formation is not related to activities of mantle plume, but is a product of the collision between the Cathysian and Yangtze blocks. The existence of microgranitoid enclaves in the SP granites may indicate the injection of deep basic magmas. These SP granites are post-collisional ones. The underplating of the asthenosphere-derived basic magmas provided a thermal source for the partial melting of the crust rocks due to the slab breaking-off after collision. The ascending magmas trapped the fragments of the country rocks, and finally emplaced in the mid-lower crust.