The (0 0 1) surfaces of SrTiO 3 with oxygen vacancy were studied with the first-principles calculations based on the generalized gradient approximation supplemented by the LDA+ U method. Strong local spin and orbital polarization of the Ti 3d electrons induced by oxygen vacancy are found. For SrO-terminated case, the occupied Ti 3d orbital has strong 3 z 2– r 2 character, while for TiO 2-terminated case, one of the t 2g orbitals perpendicular to the surface is occupied on each of the two neighboring Ti atoms. By allowing the spin polarization, the calculated electronic structures of TiO 2-terminated surface can well explain the scanning tunneling microscopy and spectroscopy data.