Abstract: Utilizing the method of cycle sequence stratigraphy and using actual data such as drilling,seismic and core,the authors analyze block X area in the North Yellow Sea basin. We have identified in the upper Jurassic of Mesozoic-Cenozoic Oligocene strata 11 mid-term base-level cycles,corresponding to a three-tier sequence,composed of sequence Ⅰ-sequence Ⅺ from bottom to up and we thus could establish a high-resolution drilling sequence stratigraphic framework in the study area. Based on this result and the understanding of the North Yellow Sea basin evolution and development,together with information from drilling, seismic and so on, we further study the sedimentary characteristics in the Mesozoic and Cenozoic strata of the area,and come to the conclusion that there are two sets of exploration layers and three sets of favourable reservoir and seal associations in the area. These are of important guiding sense to study the petroleum trap distribution in the study area.