Abstract: Effective finite model and reasonable grid partition are the basis for stress analysis on local defects of large tanks. In order to guarantee the calculation accuracy and reduce the burden of the finite element calculation for large tanks, the settlement and deformation of the storage tank calculated by the contact model of the elastic foundation was preliminarily analyzed. Based on the analysis, combined with the stress distribution and deformation characteristics of the bottom plate, the simplified two-dimensional storage tank model was obtained by replacing the bottom plate not uplifted and the whole foundation with the displacement on the section of the uplifted position as boundary condition. Then, through the study of the influence of the grid size on the calculation results in different directions, a suitable grid partition method was proposed and the simplified three-dimensional model of storage tank was obtained. As shown by the comparison analysis, the simplified two-dimensional and three-dimensional storage tank models are accurate enough to replace the complete elastic foundation contact model for static analysis, and the simplified model could also be used to calculate the stress intensity factor of the cracks near welds and to evaluate the residual strength of storage tanks.