Designing　shape-controlled　Pt-based　core-shell　nanocrystals　is　a　prospective　strategy　to　maximize　the　utilization　of　Pt　while　maintaining　high　activity　for　oxygen　reduction　reaction　(ORR).　However,　the　core-shell　structures　with　ultrathin　Pt　shell　exhibit　limited　electrochemical　durability.　Therefore,　a　thicker　shell　is　proposed　to　successfully　improve　the　durability　of　the　core-shell　structures　by　preventing　the　core　from　dissolution.　Never-theless,　the　deposition　of　Pt　tends　to　switch　to　the　Stranski-Krastanov　(S-K)　growth　mode　with　the　increase　of　the　number　of　layer,　resulting　in　the　absence　of　a　conformal　morphology.　Herein,　we　realize　the　deposition　of　three-to-five-layer　epitaxial　Pt-Co　layers　on　Pd　octahedral　seeds　by　introducing　tensile　strain　in　the　epitaxial　layer　to　impede　the　S-K　growth.　The　as-obtained　Pd@　Pt-Co　octahedra　with　four　layers　exhibit　enhanced　mass　activity　(0.69　A/mgPt)　and　specific　activity　(1.00　mA/cm2)　for　ORR,　which　are　4.93　and　5　times　that　of　the　commercial　Pt/C,　respectively.　Furthermore,　it　shows　only　17%　decay　for　specific　activity　after　a　30,000-cycle　durability　test.　This　work　is　expected　to　enlighten　the　design　and　synthesis　of　related　core-shell　nanocrystals　with　facetted　multicomponent　shells,　offering　a　promising　strategy　for　designing　cost-effective　and　efficient　catalysts.