The adsorption of CO on Pu (100) surface were studied by the density functional theory (DFT). The calculation results show that the O-down adsorption is less stable than the C-down adsorption which is found to be a strong chemisorption. The stability of adsorption configuration of CO is hollow tilted > hollow vertical > bridge > on-top. The interaction between Pu atom and CO molecule results mainly from the contribution of hybridized molecular orbital of CO molecule and hybridized orbital of surface Pu atom. A small activation barrier of 0.280eV is found for the dissociation of CO molecule in hollow tilted configuration, which indicates the dissociative adsorption of CO on Pu (100) surface at the lower temperature with dissociated C and O atoms favoring the hollow site of lowest energy.