Based on the study of density function using first-principles theory，by studying the concentration of oxygen vacancies，the DOS and the absorption spectrum of anatase，we discovered that the high concentration of oxygen vacancies has great influence on the forbidden band gap，absorption spectrum Einstein shift and life_time of electrons，and explained the reason why the concentration of oxygen vacancy makes the forbidden band gap to narrow. At the same time，the anatase semiconductor has Mott transition when there is a high concentration of oxygen vacancies. The conclusion that suitably controlling the concentration of oxygen vacancy leads to Einstein shift is deduced by comparing the Einstein shift experiment of oxygen vacancies in anatase with that in the plasma. It offered credible data for preparation visible light activator suitably by controlling the concentration of oxygen vacancies in anatase.