Augmented reality (AR) technology integrates computer-generated virtual information into the real world, providing users with an immersive experience. AR technology is considered next-generation display technology; however, there are issues. In this paper, an optical waveguide design based on achromatic metagratings is proposed to solve the problems of chromatic aberration, color uniformity, and light field uniformity in the AR display system. The coupling response of metagratings is simulated. In the case of a single-layer metagrating, the light with three wavelengths (473, 532, and 620 nm) is incident and emitted at the same angle, eliminating chromatic aberration. Based on this, we designed a double-layer metagrating. With the double-layer metagrating, the intensity ratio and coupling efficiency of light with different wavelengths can be adjusted, and color uniformity can be improved, which is expected to be used for pupil expansion. The proposed AR display optical waveguide design based on achromatic metagratings will offer a new design idea for AR head-mounted displays.