Abstract: By taking the large thick reservoirs in Bohai A oilfield as the research object, making full use of core,drilling, logging, seismic and dynamic data, with the hierarchical interface analysis method, the configuration study of large thick sedimentary reservoirs in braided river delta was carried out, which divided the sedimentary reservoirs of the main intervals into four or five levels on interfacial configuration units, namely underwater distributary channel, channel margin, mouth bar, sheet sand and interdistributary bay. The single sand body boundary is identified by comprehensive use of such signs as number difference of interlayer, change of sand body transverse thickness, mud deposition between sand bodies, and curve shape difference. The plane and profile configurations of single sand body and the spatial distribution of sand body are determined. The study results have been applied to the fine optimization of water injection and the exploitation of remaining oil, and good results have been achieved.