Density functional theory (DFT) plays a significant role in the development of visible light responsive photocatalysts.Based on the first-principles plane-wave ultrasoft pseudopotential (USPP) method,the crystal structures of α,β,γ,and δ-Bi2O3 were optimally calculated for the total density of states (TDOS) and the partial density of states (PDOS) of Bi,O atoms.The calculation for Ti(IV) doped Bi2O3 supercell was carried out.The effects of Ti(IV)-doping on the electron structures and light absorption properties of various Bi2O3 were analyzed.The results showed that Ti 3d orbital appeared in the forbidden band of Bi2O3 and hybridized with O 2p,Bi 6p orbitals.The narrowed band gap (Eg) and red-shift of light absorption edge are responsible for the enhanced photocatalytic activity of Bi2O3.The β-Bi2O3 and Ti-doped β-Bi2O3 were prepared by a hydrothermal synthesis method.The improvement of the photocatalytic activity of Bi2O3 has also been verified by the characteristics of the UV-vis diffuse reflection spectrum and the experimental evaluation of the photocatalytic degradation of crystal violet in aqueous solution. Density functional theory (DFT) plays a significant role in the development of visible light responsive photocatalysts. Based on the first-principles plane-wave ultrasoft pseudopotential (USPP) method, the crystal structures of α, β, γ, and δ-Bi2O3 were optimally calculated for the total density of states (TDOS) and the partial density of states (PDOS) of Bi, O atoms. calculation for Ti (IV) doped Bi2O3 supercell was carried out. the electron structures and light absorption properties of various Bi2O3 were analyzed. The results showed that Ti 3d orbital appeared in the forbidden band of Bi2O3 and hybridized with O 2p, Bi 6p orbitals. The narrowed band gap (Eg) and red-shift of light absorption edge are responsible for the enhanced photocatalytic activity of Bi2O3. The β-Bi2O3 and Ti-doped β-Bi2O3 were prepared by a hydrothermal synthesis method. The improvement of the photocatalytic activity of Bi2O3 has also been verified by the characteristics of the UV- vi s diffuse reflection spectrum and the experimental evaluation of the photocatalytic degradation of crystal violet in aqueous solution.