Limited　by　the　sluggish　kinetics　at　the　cathode　of　proton　exchange　membrane　fuel　cells　(PEMFCs),　optimizing　platinum-based　alloy　catalysts　for　oxygen　reduction　reaction　remains　a　key　target　toward　industrialization.　Strain　engineering　is　widely　employed　to　tune　Pt-M　catalysts,　but　its　impact　on　the　structure-property　relationship　is　often　interwoven　with　multiple　factors.　In　this　work,　we　propose　a　bi-stage　strain　tuning　method　and　demonstrate　it　on　the　most　common　PtCo　catalysts.　Macro-strain　is　introduced　by　synthesizing　single-crystal　PtCo　nanodendrites,　whereas　mild　acid　etching　introduces　micro-strain　to　the　surface.　The　half-wave　potential　of　as-treated　catalysts　reaches　0.959　V,　and　mass　activity　is　up　to　0.69　A　mg-1　Pt　.　A　minimal　decrease　of　2　mV　is　observed　for　half-wave　potential　after　10,000　cycles.　Detailed　analysis　using　advanced　transmission　electron　microscopy,　wide-angle　X-ray　scattering,　etc.　provides　direct　evidence　that　surface　disorder　at　the　atomic　scale　accounts　for　the　enhanced　activity　and　stability.　In　contrast,　the　simplicity　of　this　approach　allows　for　scaling　up　on　Pt-M　catalysts,　as　demonstrated　on　PEMFCs.　The　bi-stage　strain　tuning　strategy　provides　a　new　perspective　and　reference　for　improving　the　activity　and　durability　of　Pt-M　catalysts.　(c)　2025　Science　Press　and　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.　and　Science　Press.　All　rights　are　reserved,　including　those　for　text　and　data　mining,　AI　training,　and　similar　technologies.