Flexoelectricity　offers　a　number　of　advantages　in　micro/nano-scale　devices　when　compared　with　piezoelectricity　as　confirmed　through　numerous　experiments　and　theoretical　analyses.　Snap-through　behavior　in　bistable　plate　would　convey　a　higher　conversion　efficiency　for　energy　harvesting.　However,　there　is　no　theoretical　research　on　micro/nano-scale　energy　harvester　with　flexoelectricity　based　on　bistable　plate.　This　paper　describes　an　electro-thermo-mechanical　coupling　system　of　micro/nano-scale　bistable　plates　for　piezoelectric　energy-harvesting　applications.　The　nonlinear　geometric　theory　of　Von　Karman,　strain　gradient　theory,　the　flexoelectric　effect,　and　Hamilton＇s　principle　were　used　to　derive　nonlinear　dynamic　formulas.　The　ambient　vibration　frequency　and　snap-through　behavior　both　have　an　effect　on　the　output　voltages　calculated　by　Matlab　(R)　software.　An　expression　for　the　energy　conversion　efficiency　of　the　bistable　plate　was　derived　and　the　influence　of　resistance　on　this　efficiency　was　investigated.　The　result　showed　that　the　snap-through　behavior　delivered　a　large-amplitude　vibration　and　a　higher　output　voltage　at　the　range　of　one-third　super-harmonic　resonance　(2.8-3.5MHz)　for　the　micro/nano-scale　bistable　plate.　This　work　will　be　helpful　in　the　design　of　micro/nano-scale　bistable　plates　with　higher　output　voltages　and　improved　conversion　efficiencies　for　energy　harvesting.