At present mixosedimentite reservoir is the most important targets in the oil and gas exploration and development of the Shahejie Formation in the Shijiutuo uplift，Bohai Bay Basin. However，there are few studies on the sedimentary characteristics and the reservoir features of the mixosedimentite. Thus systematic research on the mixosedimentite reservoir is needed. Based on the data of coring，casting thin sections，logging and testing，etc.，it is concluded that the mixosedimentite in the eastern margin of Shijiutuo uplift is the mixture of the terrigenous clastic and carbonate components. And the lithology mainly includes fine sandstone containing intraclast，medium-fine sandstone containing bioclasts，conglomerate containing bioclasts，sandy bioclasts dolomite，sandy micrite dolomite containing bioclasts-intraclast and sandy bioclasts dolomite. According to the analysis of the reservoir physical properties and the result of the diagenetic evolution，the physical properties of the mixed bioclastic beach developed in the semi-closed or closed lake-bay is the best while that of bioclastic sandy beach and the bioclastic gravelly beach developed in the fan delta front is second. The main factors controlling the reservoir physical properties are lithofacies，sedimentary facies，compaction，cementation and dissolution，among which lithofacies and sedimentary facies are the precondition for the formation of high quality reservoir. Compaction plays a less important role on physical properties of reservoirs due to its suppression. In contrast，the late diagenesis，such as cementation and dissolution，are more important for improving reservoir physical properties.