The beach-bar reservoir is one of the most important targets of oil-gas exploration and development in recent years. Sha-2 member of Banqiao Sag develops typical thick layer lacustrine beach-bar sand bodies. The single sand bodies can be up to 10m thick, and usually form compound beach-bar sand bodies with well developed interbeds and tens of meters thick in vertical profile. The beach-bar sand body is further divided into 5 types of microfacies, namely key bar, side-portion of bar, between-portion of bar, nearshore beach and offshore beach, based on the sedimentary characteristics, plane configuration and developing locations of them in the study area. On the basis of the integrated study of paleotectonics and sedimentary environment, this paper points out that the thick beach-bar sand bodies in this area are formed by the organic combination and collective control of source, hydrodynamics and contemporaneous faults both in time and spatial. The braided river delta sand bodies from the south are the main source and material basis of beach-bar sedimentary in Banqiao Sag. Hydrodynamic action is of large area in the gentle slope, and controls the scale and distribution of beach-bar sand bodies. The change of wave energy influences the microfacies differentiation of beach-bar. The contemporaneous fault is the dominant factor. On one hand, the contemporaneous fault controls the allocation of the material from source, which result in abundant sediments supply in the downthrown wall. The fault fractured surface is of persistently high hydrodynamic energy, and gradually forms thick layer beach-bar sand bodies. On the other hand, the activity of the contemporaneous fault adds the possibility of the base level rising in the downthrown wall and provides enough time for the deposition of beach-bar, thus the sand bodies will no longer stagger stack caused by the frequent change of the base level in a short time but deposit persistently to thick layers vertically. The downthrown wall of the contemporaneous fault is the favorable position for the thick layer beach-bar sand bodies development where structural-lithologic traps are easily formed and conducive to oil-gas accumulation.