The　nonlinear　trends　of　composite　laminated　plates　are　investigated.　The　governing　equations　of　motion　for　the　plate　are　derived　with　the　von　Karman　strain-displacement　relations　for　the　geometric　nonlinearity　and　the　Reddy＇s　third-order　shear　deformation　plate　theory.　The　four　dimensional　nonlinear　averaged　equations　with　the　case　of　1/2-subharmonic　resonance　and　principal　parametric　resonance　for　the　first　mode　and　primary　resonance　for　the　second　mode　are　obtained　by　applying　the　method　of　multiple　scales.　The　frequency-response　curves　are　analyzed　under　consideration　of　strongly　coupled　of　two　modes.　The　influences　of　the　coefficients　in　dynamic　equations　and　the　detuning　parameters　on　the　nonlinear　trend　are　studied,　and　the　results　indicate　that　the　composite　laminated　plate　may　have　different　trends　of　nonlinearity　under　aforementioned　resonance　conditions.　The　sweep　experiment　is　conducted　to　find　the　softening　and　hardening　nonlinearity.　The　different　trends　are　obtained　when　the　excitation　amplitude　is　1.2g.　The　spectrums　of　the　different　stages　of　the　test　show　that　the　change　of　the　nonlinear　trend　may　be　caused　from　the　sub-harmonic　resonance　in　this　test.　Copyright　©　2012　by　ASME.