Under UHV condition, the C-O stretching mode properties of diacetate cellulous (C2H8O3-(COOCH3)2) adsorbed on polycrystalline Ag surface were studied by using PAS. The peakpo-sitions, and the peak shifts and FWHM's, of the vibrational mode at different adsorbate coverages and different temperatures were demonstrated. Some features of adsorption of macromolecules on metal are discussed. The results also show that our facilities has the satisfactory sentivities for surface submonolayer detection.