Optical gas sensor material adsorption gas molecules lead to changes in optical properties to detect environmental gas composition, which is called optical gas sensing effect. Microscopic characteristics of rutile titanium dioxide (110) surface adsorption H2S molecules are studied, under the first-principles plance-wave ultrasoft pseudopotential method based on density functional theory (DFT) system, and adsorption energy, charge density, density of states and optical properties of TiO2 (110) surface are calculated. The results show that, the most stable surface is TiO2 (110) surface which terminated on the two coordinated O atoms; only containing oxygen vacancy surface can stably adsorb H2S molecules; the higher of the oxygen vacancy concentration, the higher adsorption energy; the main way of surface adsorption H2S molecules is horizontal adsorption. When oxygen vacancy concentration reach 33%, adsorption energy is 0.7985 eV. The adsorption essence is surface oxygen vacancies oxidation H2S molecule. In the visible light range of 400~760 nm, the surface optical properties can be improved only when H2S molecules adsorption on containing oxygen vacancies surface, moreover, the higher concentration of oxygen vacancy, the more obvious improvement of absorption, reflection ability and optical gas sensing performance.