By using the plane_wave ultrasoft pseudopotential method, the geometric parameters, electric and optical properties of Rb2TeW3O12 are investigated. The equilibrium lattice constants are in good agreement with experimental data. The electric structures reveal that Rb2TeW3O12 is a direct wide_band semiconductor and the band gap is 223eV; W 5d and O 2p states form a strong W— O covalent bond. Optical properties have been studied and we have presented the dielectronic functions ε1 and ε2. Static dielectric constant　ε 0=529 have been gained.