OAPA　Flight　performance　calculation　is　an　important　part　of　the　micro　flapping　wing　air　vehicle　design.　It　is　used　to　verify　whether　the　air　vehicle　design　meets　the　performance　requirements　so　as　to　make　targeted　improvements　to　the　design.　It　also　provides　a　reference　for　the　flight　test　of　the　micro　flapping　wing　air　vehicle.　The　calculation　methods　for　the　flight　performance　of　the　fixed-wing　air　vehicle　and　the　rotorcraft　cannot　be　copied　for　the　flight　performance　of　the　flapping　wing　air　vehicle.　The　paper　first　builds　the　energy　theory　and　slipstream　theory　of　the　flapping　wing　flight,　providing　a　calculation　method　of　the　power　required　for　the　flapping　wing　flight.　Based　on　the　design　data　including　performance　requirements　of　the　flapping　wing　air　vehicle,　overall　parameters　and　wing　drive　system　performance,　the　paper　proposes　the　calculation　methods　for　the　flight　performance　such　as　the　level　flight　performance,　climb　performance　and　endurance　performance　of　the　flapping　wing　air　vehicle.　The　paper　compares　the　flight　performance　calculation　results　of　flapping　wing　air　vehicle　prototype　with　flight　test　data,　which　illustrates　the　rationality　of　the　calculation　methods　proposed.