We　applied　periodic　density-functional　theory　to　investigate　the　adsorption　of　C2H2　on　the　Cu/Pt　bimetallic　and　monometallic　surfaces,　including　Cu-Pt-Pt　and　Pt-Cu-Pt　representing　the　monolayer　Cu　on　the　Pt　surface　and　subsurface　Cu　in　the　Pt　surface,　respectively.　For　the　Pt(111)　and　Pt-Cu-Pt　surfaces,　C2H2　is　preferentially　a　3-fold　＂parallel-bridge＂　configuration,　and　a　＂mu-bridge＂　structure　exists　above　the　Cu(111)　and　Cu-Pt-Pt　surfaces.　The　adsorption　energy　of　C2H2　on　these　surfaces　decreases　in　the　order　Pt(111)　＞　Cu-Pt-Pt　＞　Pt-Cu-Pt　＞　Cu(111).　The　analysis　of　density　of　states,　charge,　and　vibrational　frequencies　showed　obviously　weakening　of　the　adsorbed　C-C　bond　and　high　sp(2)　character　on　the　carbon　atom.　Furthermore,　when　the　top-layer　compositions　are　equal,　the　hearer　the　E-F　d-band　center　is,　the　larger　the　C2H2　adsorption　energy　will　be.