Abstract: The traditional plate tectonics and its derivative plate collision theory have been sucessfuly applied in explaining the plate motion and formation of orogenic belts However，they are now in the face of many difficulties in explaining many geological phenomena after the final convergence of plates，such as rapid uplifing of orogenic belts，exhumation of high to ultra-high pessure metamorphic rocks and extensive magmatism,and so on. Post-orogenic magmatism, as one of the most important manifestations to reflect the adjusment and transition of themal-stress structure in orogenic belts，its petrogenesis is crucial for understanding the entire evolution of orogenic belts．It generally shows lithological assosiations characterized by：(a)bimodal volcanism ；(b)high-K calc-alkaline to shoshonitic characters and(c)massive granitic plutons. Due to their melting sources having been modified by previously subducted continental／oceanic crust，the post-orogenic basaltic magmas generally exhibit similar geochemical characteristics to those of island arc volcanic rocks. For instance, strong LILE and LREE enrichment and significant HFSE depletion. Comparing with thoze of IAB，they usually possess higher K2O 十Na2O and((Fe203+FeO)／((MgO)，((K2O)／((Na2O)ratios as well as higher Sr contents and Zr／Y rarios. Additionally,they exhibit enriched Sr and Nd isotopie ratios in relation to those of MORB and OIB，which are determined by the degree of LILE and LREE enrichment as well as the characters of subducted crust. For the basaltic magmas，they are derived from decompressional melting of metasomatized continental lithospheric mantle formed during previous plate subduction in response to unrooting of the thickened lithosphere，whereas the felsie magmas can be generated either by means of differentiation of basaltic melts in crust-level magma chamber，or remelting of lower／middle crust as a result of basaltic underplating. The mechanism for extensive melting during post-orogenic stage is closely related to extensive horizontal movement along lithosphere-scale faults that triggers lithospherie extension and thinning．For most of the post-orogenic magmatism in eastern China，which is characterized by low MgO an d high Si02 contents and absence of OIB-like melts and had undergone strong magma differentiation before their emplacement，a diffusive rather than rapid extension impacted by upwelling mantle plumes is preferred.