Abstract: There are few volcanic activities during early Mesozoic in SE China. Late Mesozoic large scale volcanic magmatism started from middle Jurassic, continued for a duration of 100 Ma and became most intensive in early Cretaceous, resulting in formation of widely distributed late Mesozoic volcanic-intrusive rocks in this region. Cenozoic magmatism is shown by small scale basaltic magma eruptions along the coast. Three volcanic belts are studied in this paper, which include a nearly east-west （EW） trending late Mesozoic volcanic belt distributed across south Hunan, south Jiangxi and southwest Fujian, a nearly north-northeast （NNE） trending late Mesozoic volcanic belt distributed in Zhejiang and east Fujian, and a nearly NNE trending Cenozoic volcanic belt overlies on NNE trending late Mesozoic volcanic belt. By comparison of the geochemical characteristics of basalts from the three volcanic belts, integrating their temporal and spatial distributions, the geneses of the magmas and related crust-mantle interactions as well as the tectonic settings are discussed. Along the nearly EW trending volcanic belt from inland toward coast, the lithology of basalts changes from alkaline to tholeiitic, and the amount of erupted volcanic rocks and the proportions of rhyolites coexisting with the basalts increase. This episode （180 - 170 Ma） of magmatism, formed in within-plate tectonic setting, is the incipi- ence of large-scale late Mesozoic magmatism in SE China and an indicator of conversion from EW strike Tethys tectonic system to NNE strike Pacific tectonic system. The geochemical studies of the basalts indicate crustal contamination increases from the inland to the coast along the volcanic belt, and therefore show different degrees of crustmantle interactions. The nearly NNE trending volcanic belt is dominated by rhyolites and coexisted with minor amount of andesites and basalts. The volume proportion of basalts is less than 30% even in bimodal volcanic rocks. The basalts are mainly of calc-alkaline series rather than tholeiites. Their geochemical characteristics show their formation in island arc tectonic setting. This episode （130 -90 Ma） of magmatism is the climax of large scale volcanic magmatism in SE China constrained by Pacific dynamic system. Extensive crust-mantle interaction was reflected by higher degree of crustal contamination of basalts, and formation of andesitic rocks due to magma mixing between underplating basaltic magma and overlying acidic magma generated from partial melting of crust. The nearly NNE trending Cenozoic volcanic beltis, distributed in the coastal area of Zhejiang and Fujian provinces and dominated by alkali basalts bearing a large amount of mantle xenoliths. Their occurrence is constrained by a series of NNE trending faults of continental margin. Their geochemical signatures show their for mation in typical rifting rifting tectonic setting and therefore their occurrence is an indicator of a turn from island arc tectonic setting into tectonic setting of continental margin. These Cenozoic basalts were generated from asthenospheric mantle and accompanied by an EMII component, but had no obvious crustal contamination.