Abstract: The petrophysical characteristics and sedimentary microfacies type of the lacustrine carbonate rocks in the lower Sha?1memberof Shahejie formation in the southwestern margin of Qikou sag are classified by means of core description, thin section observation and well logging interpretation. The lithology in this study area includes bioclastic limestone, oolitic limestone, micrite, micritic dolomite, dolomitic limestone and lime dolomite. The sedimentary microfacies of carbonate rocks are classified as particle beach, dolomitic limestone lake?bay and dolomitic bottom land. Through the analysis of different lithology logging response characteristics, the logging curve numerical characteristics of various types of carbonate rocks are summed up, and the logging identification chart for such carbonate rocks in this area. Also, the sedimentary facies models for the western slope area and the eastern step?fault zone in this area are established, respectively on the basis of analysis of the microfacies characteristics and sedimentary setting. This paper suggests that the areas surrounding the western slope swells lack of charge of terrigenous clastic materials, which allow the particle beach in high energy environment and the dolomitic limestone lake?bay and dolomitic bottom land in low energy environment to coexist, while in the areas surrounding the eastern step?fault zone swell there exist charges of terigenous clasitc materials, but only develop the lake?bay and bottom land. The sedimentary models are helpful to the carbonate reservoir prediction in the similar areas in Bohai Bay basin