Abstract: As the major exploration and evaluation target of lithologic type oil and gas reservoirs of continental shallow shore lake facies, the beach bar sand body shows more and more important position in increasing reserves in recent years. The formation mechanism and spatial distribution law of beach bar sand body in the second member of Shahejie Formation (Sha 2 member) in Qibei slope in Qikou Sag are analyzed to guide the exploration in the oilfield. The analysis of paleo sedimentary settings indicates that beach bar sand body was mainly developed in the early stage of base-level rising half cycle, with the largest scale in Bin Ⅳ^U and Bin Ⅲ^L oil groups; The distribution of thick bar sand body was controlled by underwater paleo uplift and influenced by the sufficient material supply by the adjacent provenance, repeatedly turbulent hydrodynamic force, and the shape of lake basin floor. The forward seismic modeling technique enables to define the seismic response characteristics of thick bar sand body. The threshold value of low frequency-strong amplitude of thick bar sand is determined by spectrum analysis, and the favorable zone for the development of thick bar sand is predicted by using low frequency-strong amplitude attribute fusion technology. Based on the exploration practice, the exploration and evaluation method of beach bar sand body is established, namely,delineating the range of beach bar in shallow water area with wide and gentle structure, searching for thick bar sand in underwater paleo uplift, and determining the favorable zone for the development of thick bar sand by low frequency-strong amplitude attribute fusion method.The research results guided the selection of three favorable zones with bar sand developed in Sha 2 member in Qibei slope, and commercial oil flows were obtained in all four wells, with a drilling success rate of 100%. The exploration practice shows that the beach bar sand body is well developed in Qibei slope, and the thick bar sand is characterized by oil enrichment and high-yield production, which shows an important replacement field and orientation for increasing reserve and production in mature oil area.