The results of seismic exploration and drilling indicate that Mesozoic exists in the northern South China Sea (SCS). The sedimentary models of Mesozoic and the facieses of seismic are different from west to east across the northern SCS. According to the seismic profiles, the Mesozoic sedimentary distribution in the northeast part of the SCS has double-layer structure, but the Mesozoic distribution in the northwest part of the SCS has mono-layer structure. In the northeast part of the SCS, Mesozoic strata are com-posed of Jurassic marine sediments and Cretaceous continental sediments; in contrast, in the northwest part of the SCS, Mesozoic strata are only composed of Cretaceous continental sediments. According to the direction of seawater-intrusion, the sedimentary en-vironment of Mesozoic was correlated to paleo-Pacific other than Tethys. During Jurassic, paleo-Pacific covered the east of the Pearl River Mouth Basin and Taixinan Basin. From early to late Jurassic, the area of marine basin became less. During Cretaceous, the northern part of the SCS uplifted as a whole, except the east of the Taixinan Basin. During this period, small faulted basins were de-veloped and accommodated continental sediments. The northern South China Sea located in the junction area of Tethys tectonic do-main and the Pacific tectonic domain during Mesozoic; the sedimentary model clears further the control effect of Pacific Ocean structural domain to South China Sea. The northeast part of South China Sea would be beneficial areas for oil and gas exploration.