A numerical approach for forming simulation and manufacturing of micro part, based on the elastic and the rigid-plastic finite element methods by using grain element and grain boundary element, is proposed to simulate MEMS/micro-structural deformation behavior of material during micro forming. The idea is to present the polycrystalline material by an aggregate of so-called grain element that describes the plastic deformations of each individual grain in view of micro-structure. This grain element is connected by grain boundary element to account for shear deformation between grains. The main objective in this study is to develop the reliable finite element model and scheme for micro forming simulation with very thin sheet. The reliability for micro forming analysis is described from the comparisons of the micro-structural deformation behavior between the conventional rigid-plastic finite element analysis and the FE analysis of the developed program with very thin sheet material.