Several different Pd/Au(100) alloy surface configurations are built, the surface properties and reagents adsorption are systematically studied using periodic DFT methods.The electronic effect induced by alloying with Au causes the Pd d-band to be more localized below the Fermi level.And it is the dominant factor that affects the chemisorption of ethylene.While the geometric effect plays an important role in the C-C bond weakening of the chemical-adsorbed ethylene and the chemisorption process of acetate species.Acetic acid is physically adsorbed on the different alloy configurations with similar structures.Adsorption energies and vibrational frequencies of the reagents are in good agreement with available experimental and theoretical results.The study is essential for the catalytic performance enhancement and mechanism investigation of the vinyl acetate synthesis.