Based on the data of core analysis and logging and 3D seismics, a high- resolution isochronal stratigraphic framework is set up for each gas pay bed in LD15-1 Gas Field in Yinggehai Basin. One sedimentary facies (non- barrier coast facies), two subfacies (shoreface and offshore subfacies) and three microfacies (shoreface bar, offshore beach and offshore mud microfacies) are identified. As a result, a model of vertical sedimentary evolution is proposed and the distribution maps of sedimentary microfacies for main gas pay beds are described.