The　nonlinear　behaviors　and　energy　harvesting　of　an　unsymmetric　cross-ply　square　composite　laminated　plate　with　a　piezoelectric　patch　is　presented.　The　unsymmetric　cross-ply　square　composite　laminated　plate　has　two　stable　equilibrium　positions　by　applying　thermal　stress,　thus　having　snap-through　with　larger　amplitude　between　the　two　stable　equilibrium　positions　relative　to　the　general　laminated　plate.　Based　on　the　von-Karman　large　deformation　theory,　the　nonlinear　electromechanical　coupling　equations　of　motion　of　the　unsymmetric　composite　laminated　plate　with　a　piezoelectric　patch　are　derived　by　using　Hamilton＇s　principle.　The　influence　of　the　base　excitation　amplitude　on　nonlinear　behaviors　and　energy　harvesting　are　investigated.　For　different　base　excitation　amplitudes,　the　motions　of　the　system　demonstrate　periodic　motion,　quasi-periodic　motion,　chaotic　motion　and　snap-through,　and　two　single-well　chaotic　attractors　and　a　two-well　chaos　attractor　coexist.　Moreover,　the　power　generation　efficiency　is　optimal　when　the　excitation　amplitude　is　in　a　certain　range　due　to　its　own　unique　nonlinear　characteristics.　The　unsymmetric　cross-ply　square　composite　laminated　plate　subjected　to　thermal　stress　can　actually　be　called　a　kind　of　bistable　composite　shell　structure　that　has　a　broad　application　prospect　in　combination　with　morphing　aircraft,　large　deployable　antenna　and　solar　panel,　which　are　very　likely　to　have　nonlinear　vibration.