Modern integrated optical instruments often have many functions, the working bands of optical systems may cover ultraviolet, visible, glimmering, near infrared, shortwave infrared, even mid-infrared and far-infrared wavebands. Such optical systems are often more complex, containing more types of optical parts, there is loss of light energy in the mirror and severe stray light, which results in lower brightness, contrast and image resolution. In order to obtain good optical system performances, ultra-wideband antireflection coating is needed on the surface of the optical parts. This film system usually needs more layers and combinations of many kinds of film materials, the design and deposition are very difficult. A kind of ultra-wideband antireflection film designed with passband expansion method is proposed. Two kinds of material combination such as Ta2O5 and SiO2 are selected to obtain antireflection effect at ultra-wideband, so we can get the Rave is less than 1.6% at 0.42～0.9 μm, Rave is less than 1% at 1.064±0.01 μm and Rave is less than 1% at 1.57±0.01 μm. The quality of the desposition film meets JB/T8226.1-1999 standards.