Exploration and application of the gas sensitive sensor material of metal oxide optics is a hot issue. The adsorption energy, adsorption distance, density of states and optical properties were studied from the plane wave ultra-soft pseudo-potential technology based on the density function theory(DFT). The results through simulation calculation of CO₂ adsorbed on the anatase TiO₂ (101) surface show that only containing oxygen vacancy surface can stably adsorb CO₂ molecules; the higher of oxygen vacancy concentration, the more obvious adsorption effect. The adsorption energy is positive value when CO₂ molecules horizontal adsorption on surface, the best adsorption model is CO₂ molecules horizontal O-terminal dsorption on surface with two oxygen vacancies. Compared with the density of states, a new peak appears nearby the fermi level because of surface with oxygen vacancies and 2p electrons of CO₂ molecules doping in surface. The transition probability, optical gas sensitive features, absorption coefficient and reflectivity can be improved in the low-energy scope of visible light.