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Continental margin of South China Sea was divided into two parts for seafloor spreading in Cenozoic�� Liyue block and continental margin of northern South China Sea should be the same margin before seafloor spreading�� Based on drilling data from northern and southern continental margins of South China Sea and seismic profile interpretation across the wells��Mesozoic strata are devided into four seismic sequences and three structural layers�� Tectonic sequences and provenance analysis of northern and southern continental margins showed that the Liyue block and continental margin of northern South China Sea collided in Early Cretaceous�� In Early Cretaceous�� depositional environment in continental margin of northern South China Sea evolved from marine-continental transitional facies to continental facies��and Liyue area from shallow sea facies to littoral facies correspondingly��which showed the same upward shoaling cycle��indicating the two areas had unified tectonic and depositional setting after the collision of northern and southern continental margins�� By the end of Late Cretaceous��the two areas upheaved to be continent and have been destroyed��which caused that partial Upper Cretaceous strata in northern continental margin of South China Sea was destroyed and complete Upper Cretaceous strata in Liyue area closer to subduction boundary was destroyed��