We　applied　periodic　density-functional　theory　to　investigate　the　adsorption　of　HCN　on　xNi@Pt(111)　bimetallic　surfaces　(x　=　1　similar　to　4).　The　results　have　been　compared　with　those　obtained　on　pure　Ni(111)　and　Pt(111)　surfaces.　For　all　bimetallic　surfaces,　HCN　is　preferentially　tilted　with　the　CN　bond　parallel　to　the　surface,　and　adsorption　energies　increase　with　an　increasing　number　of　layer　Ni　atoms　on　the　surface.　The　adsorption　energies　of　HCN　on　all　bimetallic　surfaces　are　larger　than　that　on　the　Pt(111)　surface,　whereas　the　adsorption　energies　of　HCN　on　3Ni@Pt(111)　and　4Ni@Pt(111)　are　larger　than　that　on　theNi(111)　surface,　indicating　that　the　introduction　of　Ni　to　the　Pt　catalyst　could　increase　the　activity　of　bimetallic　catalyst　in　the　hydrogenation　reaction　for　nitriles.　Larger　adsorption　energy　of　HCN　leads　to　a　longer　C-N　bond　length　and　a　smaller　CN　vibrational　frequency.　The　analysis　of　Bader　charge　and　vibrational　frequencies　showed　obvious　weakening　of　the　adsorbed　C-N　bond　and　an　indication　of　sp(2)　hybridization　of　both　carbon　and　nitrogen　atoms.