For　the　classical　nonlinear　research　of　low-order　modes　of　Lamb　waves,　this　paper　firstly　introduces　the　classical　nonlinearity　derived　from　the　intrinsic　nonlinear　induced　low-order　Lamb　waves　(S0　and　A0　modes).　Theoretical　and　numerical　calculations　are　studied　in　two　aspects.　The　influence　of　nonlinear　effects　on　the　nonlinear　effects　of　classical　nonlinear　low-order　Lamb　waves　and　the　cumulative　growth　effect　are　analyzed　by　finite　element　simulation.　The　results　show　that　the　nonlinear　effect　produced　by　the　superelastic　material　model　is　greater　than　the　geometric　nonlinearity,　and　the　linear　elastic　material　model　does　not　produce　nonlinear　effects.　In　addition,　as　the　third-order　elasticity　increases　in　the　material,　the　amplitude　of　the　second　harmonic　gradually　increases.　The　second　harmonic　generated　by　the　A0　mode　with　phase　velocity　mismatch　is　the　S0　mode.　It　can　be　seen　that　the　group　velocity　matching　is　not　a　necessary　condition　for　generating　the　second　harmonic.　Since　the　phase　velocity　matching　is　not　satisfied,　there　is　no　cumulative　growth　effect;　The　higher　the　S0　mode　phase　velocity　matching　degree,　the　more　obvious　the　cumulative　growth　effect,　and　the　second　harmonic　is　the　S0　mode.　©　Published　under　licence　by　IOP　Publishing　Ltd.