The atomic structural model of the NixCu1-x disordered binary alloy was set up for the cases with or without consideration of surface segrega tion by computer program ming.Then the model of the chemisorption of CO on the surface of the material wa s set up with a coverageθ=05. The electronic structure of CO chemisorpti on on the top and hollo w sites of the NixCu1-xdisordered binary alloy was calculated (considering and not considering the segregation).The calculated results show that (1) the CO ad sorbd at top site on the surface is stable and, (2) the chemisorp tion makes the surface density of states of the disordered binary alloy lowered, the ener gy ba nd widened and the localization of d orbital weakened and, (3) the chemisorpti on of CO on the surface restricts the surface segregation of Cu, then the mutual influence of chemisorption and multiplayer surface segregation is discussed at an electronic level.