Via CASSCF/MRCI and RSPT2 calculations (single and double excitation with Davidson correction) the potential en- ergy curves of 20 electronic states in the representation ^2S+1Λ^（±）of the molecule SiO have been calculated. By fitting these potential energy curves to a polynomial around the equilibrium internuclear distance r_e, the harmonic frequency ω_e, the rotational constant B_e, and the electronic energy with respect to the ground state T_e have been calculated. For the considered electronic states the permanent dipole moment μ have been plotted versus the internuclear distance r. Based on the canonical functions approach, the eigenvalues E_v, the rotational constant B_v and the abscissas of the turning points r_min and r_max have been calculated. The comparison of these values to the experimental and theoretical results available in the literature is presented. In the present work 8 higher electronic states have been studied theoretically for the first time.