Abstract: Liyue basin is a large-size Mesozoic-Cenozoic superposed basin, which is located in the east of Nansha sea areas and characterized by special geological setting and huge thick Mesozoic strata, showing great difference from other basins of Nansha sea areas. The Mesozoic marine strata, with a thickness of more than 4 000 m, mainly consist of three sets of strata, that is, littoral-neritic coal-bearing clastic rocks or hemipelagic shales of Upper Jurassic-Lower Cretaceous, delta-neritic sandstone and mudstone of Upper Triassic-Lower Jurassic and pelagic silicite of Middle Triassic, displaying good hydrocarbon-generation potential. Liyue basin was located in the continental margin of South China in the past, now in the east of Nansha sea areas, and its Mesozoic strata have the basic petroleum geological conditions to form oil reservoir and good hydrocarbon resources potential. Mesozoic oil and gas exploration has very important significance and probably become an important new window for sea oil and gas exploration.