Structure stability and electronic structures of anatase TiO2(101) surface modified by noble metal Pt and Au have been investigated using plane-wave ultrasoft pseudopotentials. The results show that the adsorption interaction is weak between noble atoms and anatase TiO2(101) surface, resulting in a slight effect on its electronic structure. However, under O-rich condition, it is found that Pt and Au atoms are favor of the Ti vacancies. Contrary to Au atom, Pt atom tends to diffuse from surface into bulk. Under Ti-rich condition, Pt and Au atoms are favor of the O vacancies. The calculated electronic structures of possible vacancy defects indicate that the appearance of surface vacancies not only avails to wet anatase TiO2(101) surfaces, but also enables their atoms to appear 5d impurity energy levels in band gap.