Utilized　as　an　oxygen　reduction　reaction　(ORR)　catalyst　for　magnesium-air　battery,　multi-walled　carbon　nanotubes　(MWCNTs)　supported　PdSn　bimetallic　catalyst　was　synthesized　by　a　facile　borohydride　reduction　method.　Heat-treatment　was　applied　to　improve　the　catalytic　activity　and　stability　by　tailoring　the　alloying　content　and　surface　components　of　the　catalyst.　Results　illustrated　that　the　24　h　heat-treated　PdSn/MWCNTs　exhibited　best　alkaline　ORR　performance　with　low　over-potential,　high　diffusion-limited　current　density　and　superior　stability.　A　magnesium-air　battery　employing　the　24　h　heat-treated　PdSn/MWCNTs　as　cathodic　catalyst　showed　higher　discharging　power　density　and　enhanced　durability　compared　with　those　employing　the　unheated　sample　and　commercial　Pd/C　catalyst.