The relationship between the electromagnetic shielding characteristics and the infrared transmittance of the metal grid is analyzed through theoretical calculation. It is found that the electrical characteristics of the metal grid are contrary to the optical characteristics. In order to ensure that the transmittance of the optical lens decreases by less than or equal to 5% and the shielding effectiveness is greater than 30 dB (frequency range: 14 kHz－18 GHz) after metal grid plating, it was first found through theoretical calculation that selecting a metal mesh (Ni-Ag) with a line width of 10 m, a period unit length and width of 500 m, and a film thickness of 1 m can meet the requirements. Then, using DC magnetron sputtering technology, the surface of the Zinc sulfide substrate with a diameter of 100 mm was filmed. After exposure, development, hardening, corrosion, stripping and other processes, the infrared window sample with Ni-Ag frequency selective surface(FSS) grid plating was finally obtained. Finally, the infrared window sample was tested for transmittance and shielding effectiveness. The test results met the design requirements. The calculated data can be used to predict the electromagnetic shielding performance of the optical window and provide a reference for the subsequent design work.