The photoemission spectra with a sychrotron radiation of (3×1) Na adsorbed orderly and disor-derly on Si(lll)-7×7 surface are analyzed and compared with the spectra of clean Si(lll)-7×7 surface. Na atoms are not simply adsorbed on the adatoms or rest atoms. The formation of the Schot-tky barrier is decided by the interaction between Na and Si atoms and seem to bear no relation to the surface structure. The Schottky barrier height(SBH) from experimental data is agreement with the value estimated by MIGS theory.