In order to meet the requirement of low electromagnetic scattering in optical instrument windows, 1-bit metasurface based on random mesh grids is discussed in this study, and coding metasurface is arranged with chessboard structure to achieve high optical transparency and low electromagnetic scattering in instrument windows. Before and after transparency, the phase response of the metasurface unit is consistent, and the external terahertz beam can be effectively reflected. In the range of 11.0–16.0 GHz, the weakening of electromagnetic scattering by the experimental sample can reach more than 10 dB. Compared with the control sample, the transparent metasurface composed of modulation units can achieve more than 6 dB electromagnetic scattering reduction in the range of 11.0–14.0 GHz. The proposed optically transparent metasurface has high optical transmittance and terahertz wave reflectivity, and has the characteristics of broadband and low electromagnetic scattering, which provides a new design idea for transparent windows with low electromagnetic scattering.