Based on density functional theory calculations, the electronic structure and magnetic properties of C-doped BaTiO3 are investigated. It is found that the BaTiO3 doped by a nonmagnetic 2p light element (C) is ferromagnetic. The local magnetic moment is mainly localized on doped C atoms for Csub, while ferromagnetism in Cins comes from precipitation of magnetic ions Ti3+. Our results indicate that the proposed C-doped BaTiO3 is a potential candidate for dilute magnetic semiconductor material and multiferroics material.