Density-functional theory within the local density approximation + Hubbard U approach was used to study interface electronic structures in stoichiometric and oxygen-deficient LaAlO 3 /SrTiO 3 (LAO/STO) superlattices with regularly spaced n-type and p-type interfaces. Asymmetric behaviors between complementary n-type and p-type interfaces were revealed in terms of orbital-selective charge transfer. Extra electrons induced by oxygen vacancies at the p-type interface easily spread to the n-type interface and occupy the Ti 3d xy orbitals, while those induced by the vacancies at the n-type interface are strictly confined and reside in Ti 3d x 2 −y 2 and/or 3d 3z 2 −r 2 orbtials. The electronic behavior of oxygen vacancies at the LAO/STO interfaces and the possibility of distinguishing between intrinsic electronic states, which are induced by the polar catastrophe, and extrinsic states due to oxygen vacancies are discussed in detail.