Surface　and　strain　engineering　are　two　effective　strategies　to　improve　performance;　however,　synergetic　controls　of　surface　and　strain　effects　remains　a　grand　challenge.　Herein,　we　report　a　highly　efficient　and　stable　electrocatalyst　with　defect-rich　Pt　atomic　layers　coating　an　ordered　Pt3Sn　intermetallic　core.　Pt　atomic　layers　enable　the　generation　of　4.4%　tensile　strain　along　the　[001]　direction.　Benefiting　from　synergetic　controls　of　surface　and　strain　engineering,　Pt　atomic-layer　catalyst　(Ptatomic-layer)　achieves　a　remarkable　enhancement　on　ethanol　electrooxidation　performance　with　excellent　specific　activity　of　5.83　mA　cm(-2)　and　mass　activity　of　1166.6　mA　mg　(-1)(Pt),　which　is　10.6　and　3.6　times　higher　than　the　commercial　Pt/C,　respectively.　Moreover,　the　intermetallic　core　endows　Ptatomic-layer　with　outstanding　durability.　In　situ　infrared　reflection-absorption　spectroscopy　as　well　as　density　functional　theory　calculations　reveal　that　tensile　strain　and　rich　defects　of　Ptatomci-layer　facilitate　to　break　C-C　bond　for　complete　ethanol　oxidation　for　enhanced　performance.