In order to meet the modern military comprehensive optical instruments′ operating requirements of one-machine multi-purpose, super broadband antireflection coatings with wavelength from 500 nm to 1200 nm are studied and fabricated. The broadband antireflection coatings are fabricated using mixed material H4, SiO2 and MgF2. The error causes are analyzed through experiments, and the result is simulated and optimized by variable metric method with the help of coating design software. By changing the master tooling of each layer in the process of fabrication, the effect of thickness error on the spectral properties is eliminated. Finally, the film is deposited by home-made vacuum coater, and the average reflectivity of the film is below 0.5% over the wavelength range from 500 nm to 1200 nm.