The atomic structural models of the(100) and (110) surface of the Nix Cu1-x disordered binary alloy were set up when surface segregation is considered or not by computer programming.Then the models of the chemisorption of O on both surfaces were set up with the coverage θ=0.5. The electronic struc ture of O chemisorbed on the (100) and (110) surfaces of the NixCu1-x disordered binary alloy was calculated (considering and not consider ing the segregation).The calculated results show that (1) the chemisorption lowe rs the surface density of states of the disordered binary alloy,the energy band is widened, and the covalent bonds between the d electron of Ni and the s and p electron of O are stronger than that of Cu, (2) the O adsorbed on the (110) surf ace is more stable than on the (100) surface, and (3) the chemisorption of O on the surface restricts the surface segregation of Cu and this kind of influence i s obvious at the first layer.