The　adsorption　of　cyanide　on　the　top　site　of　a　series　of　transition　metal　M(100)　(M　=　Cu,　Ag,　Au,　Ni,　Pd,　Pt)　surfaces　via　carbon　and　nitrogen　atoms　respectively,　with　the　CN　axis　perpendicular　to　the　surface,　has　been　studied　by　means　of　density　functional　theory　and　cluster　model.　Geometry,　adsorption　energy　and　vibrational　frequencies　have　been　determined,　and　the　present　calculations　show　that　the　adsorption　of　CN　through　C-end　on　metal　surface　is　more　favorable　than　that　via　N-end　for　the　same　surface.　The　vibrational　frequencies　of　CN　for　C-down　configuration　on　surface　are　blue-shifted　with　respect　to　the　free　CN,　which　is　contrary　to　the　change　of　vibrational　frequencies　when　CN　is　adsorbed　by　N-down　structure.　Furthermore,　the　charge　transfer　from　surface　to　CN　causes　the　increase　of　surface　work　function.