The electrochemical stability of Pt/Au(111) surface alloy was studied by density functional theory (DFT). The formation energy calculation results show that Au and Pt are not easy to form an alloy in the bulk, but can form a surface alloy on the Pt (111). The calculation results of dissolved potential further indicate that the dissolution potential of Pt atoms on the Pt/Au(111) has a good linear relationship with the number of first neighboring Au atoms, and the effect of Au on the Pt dissolution potential of the second nearest neighbor and mor...