We calculate the atomic and electronic structure of 3C- SiC（001）-（2×1） using density functional calculations within the generalized gradient approximation. The calculated results show that the atomic structure of 3C-SiC（001）-（2×1） surface can be described by dissymmetrical Si dimmer model. The bond length of Si dimmer of 3C-SiC（001）-（2×1） surface is 0.232 nm. The calculated results of electronic structure show that a prominent density of states exists at the Fermi level, so the 3C-SiC（001）-（2×1） surface has the characteristics of metal. There are four surface state bands in the gap, one of which is located near the Fermi level, another at 5 eV above Fermi level, and the others in the valence bands below Fermi level.