In this paper, the electron beam vacuum coating method was used to coat a SiO 2 film on an MgAl 2 O 4 spinel substrate. The thickness of the coating was aimed to be 925 nm based on the physics of the antireflection coatings. Atomic force microscope images revealed that the coated silica was 880 nm thick, which is close to the aimed theoretical thickness and had 2.11 nm roughness. It could enhance the transparency of the spinel substrate by being coated on it. The infrared transmittance of the sample coated with SiO 2 film in the range of 3700 nm-4800 nm was measured by a Fourier transform infrared spectrometer and reached 92.5% to 78.5%, which was about 2%-4% higher than that of MgAl 2 O 4 spinel. In addition, it was discovered that the bonding force between the coating and the substrate is determined to be about 200 MPa. The results of this study can be used for further precise design and production of antireflection coatings on the transparent materials that need more transparency.