Electronic structure and photoelectrical properties of monoclinic VO2 are studied with self consistent of charge-discrite variation-embedded cluster model (SCC-DV-Xα-ECM) method. The results show that the energy gap is 0.4411 eV and Fermi energy level is 0.00365 eV above the center of energy gap and is close with conduction band,as accords with the experimental data very well. The total energy of monoclinic VO2 (-568.18 eV) is lower than the one of rutile VO2 (-470.33 eV),so it can undergo a transition into the later with external energy such as increasing temperature. Absorption coefficient accords with the experimental data in the low frequencies and conductance is consistent with other theoretical analysis in 2.5-13.5 eV.