In this work, we report an element segregation phenomenon in two-dimensional (2D) core-shell nanoplates, subsequently resulting in the formation of yolk-cage nanostructures after selective electrochemical etching. By using PtCu nanoplates as templates, PtCu@Pd core-shell nanoplates are formed. Interestingly, during the growth of Ru on the PtCu@Pd core-shell nanoplates, due to the selective element diffusion, PtCuPd@PdCu@Ru nanoplates are obtained. After selectively etching of PdCu in PtCuPd@PdCu@Ru using electrochemical method, the PtCuPd@Ru yolk-cage nanostructures are obtained. As a proof-of-concept application, this unique nanostructure shows superior electrocatalytic activity and stability toward the methanol oxidation reaction as compared to the PtCu nanoplates and commercial Pt/C catalyst.