The ground and low-lying excited states ofMethanol(CH3OH) have been studied. The geometric parameters, energies and frequencies of the ground state and the triplet exited state were calculated by using the MP2(full)/6-311++G(2d,2p) level of theory. Beginning with the triplet state structure, the repulsive nature of the triplet state potential energy surface is explained. The vertical excitation energies of the singlet excited states of CH3OH are calculated. It is found that the theoretical results performed by the TD-DFT(b3p86/6-311++G**) method are in best agreement with the experimental results. In addition, the vertical ionization energy, the adiabatic ionization energy, the vertical electron affinity and the adiabatic electron affinity are calculated. The theoretical results could serve as a guidance for experimental investigations.