With the meandering river of Minghuazhen Formation in C Oilfield，Bohai Bay Basin as an example，a new equivalent characterization method is explored for the three-level architecture of meandering river reservoirs. The advantages，disadvantages and applicability of three common characterization methods of lateral accretion shale beddings are summarized，and the difficulties in the fine characterization of the C Oilfield are pointed out. On this basis，a new characterization method of unstructured depogrid is introduced to simulate lateral accretion shale beddings of the three-level architectures of meandering river reservoirs. The thickness and morphology of lateral accretion shale beddings simulated by the new method，compared with those by the other three methods，are more in line with their real subsurface morphology. The proposed method overcomes the problems of conventional methods such as distorting the grid，mismatching with the borehole data and being greatly affected by the grid size. The new method is used to construct the fine characterization models of the three-level architectures of meandering river reservoirs in the study area，and the numerical reservoir simulation of the models is carried out. Compared with conventional methods，the new method enables the smoother fluid migration path near lateral accretion shale beddings and the pressure recovery time closer to the real subsurface situation. Combined with the results of numerical reservoir simulation，the fluid migration modes of two types of horizontal wells under the influence of lateral accretion shale beddings are summarized to guide subsequent well deployment.