Beach-bar sand reservoir is a common oil and gas reservoir developed in various basins in China. Although it has good potential for oil and gas development, it is difficult to describe. There are relatively few studies on seismic insider reflection characteristics of beach bar sand with strong shielding. In this paper, the finite difference forward modeling of acoustic equation is carried out for the beach bar sand with strong shielding. Through the forward modeling analysis of the seismic response of the beach bar sand reservoir with strong shielding under different conditions such as different main frequency, different formation velocity and multiple sets of sand bodies, we can see that the higher the main frequency is in a certain range, the smaller the formation velocity is, and the smaller the influence range of strong shielding on the thin layer is. For multiple groups of sand bodies, the seismic response often can not directly indicate the characteristics of sand bodies, and the weak reflection signal is the result of the superposition of multiple groups of sand bodies. Combined with Sanhebei industrial area in northern Jiangsu Basin, The research ideas and countermeasures of first lifting frequency and then shielding the last 90° phase shift can effectively separate the overburden cap layer in view of the double-compound beach bar sand reservoir with complex cap layer and weak reservoir signal. Then, the influence of strong reflection on the underlying reservoir is eliminated by the de-strong shielding process. Finally, the 90° phase shift technique is used to describe the beach bar sand body, and satisfactory results are obtained, which provides a feasible method for the exploration of such complex oil and gas reservoirs.