The densities of states and the electronic structure of photocatalyst K<SUB>2La2Ti3O10 were analyzed by the first principle calculation based on the density functional theory (DFT) within plane-wave pseudo-potential.The electric structures revealed that K2La2Ti3O10 is an indirect band gap semiconductor and the band gap is 3.2 eV. The conduction band of K2La2Ti3O10 consists mainly of the Ti-3d orbital and the valence band is made up mainly of the O-2p orbital. The band structure and photocatalytic properties activity of K2La2Ti3O10 are attributed to the electronic structures which consist of Ti-3d orbital, La-5d and O-2p orbitals.