In　this　paper,　the　authors　study　the　bifurcation　problems　of　the　composite　laminated　piezoelectric　rectangular　plate　structure　with　three　bifurcation　parameters　by　singularity　theory　in　the　case　of　1:2　internal　resonance.　The　sign　function　is　employed　to　the　universal　unfolding　of　bifurcation　equations　in　this　system.　The　proposed　approach　can　ensure　the　nondegenerate　conditions　of　the　universal　unfolding　of　bifurcation　equations　in　this　system　to　be　satisfied.　The　study　presents　that　the　proposed　system　with　three　bifurcation　parameters　is　a　high　codimensional　bifurcation　problem　with　codimension　4,　and　6　forms　of　universal　unfolding　are　given.　Numerical　results　show　that　the　whole　parametric　plane　can　be　divided　into　several　persistent　regions　by　the　transition　set,　and　the　bifurcation　diagrams　in　different　persistent　regions　are　obtained.