Abstract: Beam sampling gratings are used to sample the high-power transmitted light with an efficiency of 5% which is sent into an energy meter for energy diagnostics in the final optical focusing system of ICF. This paper proposes the structure of grating pair instead of single one. The designed grating is aberration-free by choosing system parameters properly, including the distance between two gratings，inclination angle, etc. and can be used for energy diagnostics as well as pulse response and far-field image quality measurements. The calculated results show that the optical path difference decreases from 8.3 cm in the case of single grating to 8.7 mm, and the root mean square radius of image point is 0.777 μm, which reaches the diffraction limit and can meet application requirements.