Configuration admixture and excitation energies are computed for the even-parity J=0, 1, 2, valent states of 6s2, 5d2 and 6pa confiqurations of Ba. We employ a model potential method to obtain the one-electron spin-orbitals. The computed excitation energies are generally in good agreement with available experimental data, and the three configurations are found to admix heavily in the 1S0 states. The results also identify theoretically 6p2 1S0 autoionizing state which gave rise to controversy in assignments of the levels of Ba.