W81 Block is located in the northern end of central uplift in Dongpu Sag and is a deep part of the Weicheng Oilfield structure. By detailed core observation and analysis of logging data characteristics, we can identify two main types of barrier and interlayer in Sha-4 Formation, including muddy barrier and interlayer and gray interlayer. This article describes the distribution characteristics of the barrier and interlayer from three aspects: plane, crosswell profile and well group distribution. The corresponding three-dimensional distribution model of the barrier and interlayer based on structural model has been constructed, which reflects the distribution rule across the barrier and interlayer and help to guide internal dig potential development of the low permeability oilfield.