Large Goos-Hanchen(GH) lateral shift and beam deformation for the guided mode resonant filter are fully discussed. Simulation results proved that this structure could generate lateral displacement as large as 300 λ0. Light waves that experience largest lateral displacement have maximum reflectivity, so it is relatively easier for experimental verification, and would facilitate practical application for its high energy utilization. Two analysis methods based on stationary approach and Gaussian angular decomposition technique are applied, and the lateral shift properties as well as companied beam deformation is fully analyzed. Dependence of the lateral displacement depends on the incident beam width is mainly discussed. This theoretical analysis paves the wave for the next step of manufacturing and testing.