Recent results confirm that a single-atom Pt alloy effectively catalyzes hydrogenation of 1,3-butadiene. Here the C4H6 hydrogenation mechanisms on Pt doping Cu nanoparticles are studied using density functional theory simulations. The simulation results indicate that H-2 dissociation on the surfaces of pure Cu is impossible at room temperature. However, the structure of Pt-doped Cu makes hydrogen decomposition process easier. The combination of H-2 and C4H6 on the Pt single-atom site is possible since the corresponding reaction barrier values are less than 0.71 eV. The generated 1-C4H8 or 2-C4H8 molecule can not be co-adsorbed with H-2 on the Pt single-atom site. Even if H-2 is pre-decomposed as hydrogen atoms, they also can not react with C4H8 on the Pt single atom site at room temperature since the corresponding reaction barrier values are more than 0.90 eV. The co adsorption of H-2 and C4H8 on Pt diatomic sites is probable, and the further saturated hydrogenation to generate C4H10 is promising due to a small reaction barrier (similar to 0.66 eV).