Abstract: Augmented Reality (AR) system is a display system that superimposes virtual images on the real environment. Since the optical waveguide can realize miniaturization and light weight, it is the core component of the AR display system. The diffraction efficiency of the optical waveguide coupling element greatly affects the imaging quality of the AR display system. In order to improve the diffraction efficiency of the coupling element in the AR display system, in this paper a waveguide structure with multi-layer superimposed gratings is proposed. Based on the vector diffraction theory, the grating is simulated and analyzed by using the rigorous coupled wave analysis method. Simulation results show that the diffraction efficiency of a single-layer grating reaches 60%, and the diffraction efficiency of a waveguide structure with three layers of gratings superimposed reaches 85% at a field of view of 50°, which is more than 25% higher than that of a single-layer grating. The results show that the multilayer superimposed grating waveguide structure can achieve a larger field of view and diffraction efficiency so that the AR display system has a clearer viewing field.