In　this　paper,　the　dynamics　analysis　of　Micro　bistable　piezoelectric　plate　with　proof　mass　is　carried　out,　where　the　plate　center　is　fixed　but　the　quadrilateral　is　free.　The　scale　effect　is　considered　by　using　the　strain　gradient　theory.　Considering　the　coupling　effect　of　force,　electric　and　thermal,　the　nonlinear　dynamic　equation　is　established　with　the　aid　of　the　Von-Karman　large　deformation　theory　and　the　Hamilton　principle.　Firstly,　by　means　of　the　eigenvalue　method,　the　effect　of　temperature　and　voltage　on　its　natural　frequency　and　stability　is　explored　under　the　condition　of　different　internal　length　scale　parameters　and　different　piezoelectric　layer　area.　Moreover,　the　nonlinear　dynamic　response　of　the　system　under　different　external　excitation　is　studied.　It　is　found　that　with　the　increase　of　the　piezoelectric　area,　the　more　obvious　coupling　effect　of　force,　electricity　and　heat,　the　influence　on　the　system　stability　is　increased　significantly.　Temperature　and　voltage　can　stimulate　or　restrain　the　vibration　amplitude,　which　provides　a　theoretical　basis　for　vibration　control.　Meanwhile,　it　is　shown　that　the　size　effect　has　a　great　influence　on　the　structural　stiffness,　which　proves　the　necessity　to　considere　the　scale　effect　for　the　micro　structure.