Theoretical studies of oxygen 1s NEXAFS of c(22)(K+CO) adsorption on Co1010 surface have been performed by the multiple-scatterring cluster method(MSC).The results show that the bond-length of adsorbed CO molecule is longer than that of the gas-phase one by about 0.01nm.The comparison between the calculated spectra and the experimental data demonstrates that a new weak -like structure appears on the right of the original resonance.This structure comes from the indirect interaction to CO molecule due to K atoms and the substrate.