The work aims to determine the surface coating parameters of reflector antenna, and verify the influence of the surface coating parameters on the electrical performance of reflector antenna in millimeter wave band. The electrical properties of the reflector were studied by means of electromagnetic software simulation, coating sample processing and electrical performance measurement with different coating materials, different thickness of the same coating, different material combinations and other parameters. Firstly, the parameters and reflectivity formulas of various reflector surface coating materials were qualitatively analyzed, and then the electromagnetic simulation software HFSS was used to simulate the electrical properties of different surface coating parameters to compare the reflectivity parameters of infinite plane excited by uniform plane wave. Finally, on the basis of determining the coating parameters, the test samples were processed, and the electrical properties of the coating specimens were tested in 54 GHz and 183 GHz band by the receiver equivalent noise temperature measurement method. Under the consistent results of theoretical analysis and simulation calculation, the relationship between the thickness of metal layer on the reflector surface and the reflectivity was obtained. Combined with the engineering experience, the recommended thickness of the metal layer on the reflector was determined to be 1~2 microns, and the effect on the electrical performance of the reflector antenna could be ignored when the thickness of the metal layer was less than 2 microns. The effects of different kinds of metals with the same thickness on the electrical properties of the reflector were obtained. Under the guidance of theoretical analysis and simulation analysis, the processing and reflectivity of 1.8 microns aluminum + 0.1 microns SiO2 test sample were completed. The measured results are consistent with the simulation results.