Abstract: A series of clusters, M@Si₂₀（M=vacancy, Na,Ba,Zr,Cs,Ce）, in silicon based clathrate compounds are calculated using SCF-X_α-SW method to investigate the combination between Si₂₀ cage and the inside metal atom M. Local density of electronic state of these clusters shows that d orbitsof the guest atoms make considerable contribution to p-like segment of the valence band that mainlyformed by the Si₂₀ cage, which implies the coupling between guest atom and the cage exists not only inthe conduction band, but also in the valence band. Synthesis of Ce, Zr doped type-I clathrate com-pounds is possible.