According to types and associations as well as chemical composition of Mesozoic volcanic and intrusive rocks the authors have divided the Mesozoic continental margin in southeastern China into three tectonomagmatic belts: the continental margin volcanic(magmatic)arc (Cva)，the continental margin back-arc and interarc basin belt(Abv0 and the rifting volcanic (magmatic) belt(Rv)，with a thorough study of their Sr, O, Pb and Sm, Nd isotopic compositions. These characteristics show that the three belts have both similarities and differences: Cva has relatively low initial 87Sr/86Sr ratios(commonly < 0.7100)and δ180 values(mostly <10%)，remarkable variation in Pb isotopic composition relatively high εNd values(averagely -5 .3) and slightly lower fA values(crustal component);Abv has comparatively high initial 87Sr/86Sr ratios(mostly 0.7100 0.7140)and ε18O values(7%一14%0)and fairly stable Pb isotopic composition relatively low eVd values(averagely -6.3)and slightly higher fA values (averagely 0.596);Rv has relatively and quite stable initial 87Sr/86Sr ratios(averagely 0.7071)and considerable variation in δ180 values(5%0一11 .5 %0)，rather low 206Pb/204Pb and 207Pb/204Pb values，and notable variation in εNd values(-17. 5 - +2.9 , averaely -3.3)，with fA and fP values(componems of the mantle)being close to each other. As mentioned above, these isotopic compositions indicate that the mama of Cva and Abv was derived from a mixture of the depleted mantle and the upper crust in the continental margins, the former being mainly mantle source and the latter being mainly crust source and that the mama of Rv was formed by a mixed source of epicontinental or intracontinental replacement-depleted mantle and lower crust materials.