A super broadband antireflection coating used in wavelength region of 400～900 nm is designed, which shows an average reflectance 0.2% at wavelength region 410～850 nm and 0.24% at 400～900 nm. The starting design for the computer optimization is discussed. The effect of bandwidth, the difference between high and low index, out-layer index and total thickness on predicting achievable performance is analyzed. For certain bandwidth, increasing difference between high and low index and selecting out-layer material with low index are very important for achieving an excellent anti-reflectance performance. An eight-layer super broadband antireflection coating with high and low index materials of TiO2/MgF2 on the substrate K9 has been prepared. The experimental result shows that the residual average reflectance of 0.44% in the bandwidth of 520 nm can be achieved. It is proved that the design of super broadband antireflection coating with two coating materials is successful comparing with more materials used for the situation of vertical incidence.