The surface structure of the catalyst is a key factor to affect its catalytic performance toward the targeted reaction. In this work, aiming at revealing the surface structure influences of Pd-based alloy catalysts on the catalytic performance of C 2 H 2 selective hydrogenation, four kinds of surface structures of Pd-based alloy catalysts, including the core−shell Pd nL @M (M = Cu and Ag), the core−shell Pd nL @Pd x M y , the uniform alloy Pd 1 Cu 3 and Pd 1 Ag 1 , and the subsurface structure Pd 1L -M sub are engineered, and the corresponding catalytic performance is fully examined using DFT calculations. Our results reveal that the catalytic performance of C 2 H 2 selective hydrogenation is closely related to the surface structures of Pd-based alloy catalysts; among them, the