In this paper, a method for designing a mesh grating with optical terahertz transparency and weak microwave scattering is proposed. By designing a composite structure of metal mesh grating and super surface, it improves the regulation of electromagnetic scattering based on high optical transmittance and homogenizes the forward electromagnetic scattering in the microwave frequency band. In this paper, the grating unit is composed of a double C-shaped resonance cavity and a ring, and its own unit and the unit after rotating by 90° are designed as square and triangular checkerboard arrays. The simulation results show that the two checkerboard array structures have obvious electromagnetic scattering reduction effects compared with the metal mesh grids of the same size under the frontal incidence of electromagnetic waves. The frontal electromagnetic scattering reduction peak value of the square-type checkerboard structure reaches 22.91 dB, and the frontal electromagnetic scattering reduction peak value of the triangular-type checkerboard structure reaches 36.07 dB. The scheme proposed in this paper has a wide range of application potentials in protecting terahertz optical instruments and equipment from damage by microwave radiation.