The structural stability, energy band, density of states images and absorption spectra of TiO2 (101) surface and TiO2 (101) @ MoO3 system were calculated and analyzed by the first principle method. The results show that MoO3 clusters can form Mo-O-Ti bridge structure on TiO2 (101) surface, which has good stability and is beneficial to practical use. Compared with the pure TiO2 (101) surface, the adsorption of MoO3 clusters on the TiO2 (101) surface can generate empty energy levels in the intrinsic band gap, which is conducive to reducing the energy requirements for electronic transitions, and thus conducive to electronic transitions between band gaps. The absorption spectrum analysis also proves that the TiO2 (101) @ MoO3 absorption spectrum has an absorption peak at the wavelength of 420nm, and the absorption spectrum is highly higher than the TiO2 (101) surface. The corresponding wavelength of the absorption peak in this region has entered the visible light region, which can greatly enhance the utilization of visible photons, and is of great significance for photocatalysis.