Abstract: Electronic band structure, density of states and optical properties of Ba(Ti1-xSnx)O3 with different doping amount of Sn were researched by use of the first-principle plane wave pseudo-potential method based on density functional theory. The calculation results show that with increasing doping amount of Sn, band gap of the Ba(Ti1-xSnx)O3 becomes larger, Ti-O bond at the bottom of conduction band and the top of valence band occupies main position, but Ba-O bond is weakened further, dielectric constant becomes smaller, so as to reduce insulating properties of the Ba(Ti1-xSn)O3, reflectivity has greatly changed, refractive index reduces, which makes Ba(Ti1-xSn)O3 widely apply in optical component production.