Abstract: The electron states in Si-nipi doping superlattice have been calculated self-consistently by the local-density functional approximation. The rules of electron subband energies and corresponding wave functions depending upon free carrier concentration have been obtained. The excitation energies between the occupied and the nearest-neighbor unoccupied states-(01) subbands for low carrier concentrations are discussed. The forms of the electron density are described under the Hartree potential and fully self consistent potential. It is found that the influence of the free carrier exchange-correlation potential V_xc(z) on subband energies is small.