A new surface constrain modeling method is proposed herein for the lateral accretion shale beds of point bar sand by using Petrel. In order to characterize the internal configuration of point bar, top and bottom boundaries of the lateral accretion shale beds distributing with curved surface are created based on the patterns and analysis results of point bar architecture, then the reservoir architecture model is established in the point bar sand by the method of multi-order surface constrain. For ease of numerical reservoir simulation, we designed the method of nonuniform grid upscaling to ensure the accuracy of the laterally-accreted mudstone model and reduce the grids. Then, the validity of the modeling method is validated in a point bar sand of Dagang oilfield. The results show that the modeling can reflect the spatial distribution of different levels of architectural element such as channel sand body, point bar and lateral accretion interbeds, and the result can characterize the internal configuration of point bar and reflect the actual situation in the reservoir.