This　paper　investigates　the　nonlinear　bifurcation　and　chaos　characteristics　of　piezoelectric　composite　lattice　sandwich　plates　at　1:3　internal　resonance.　The　nonlinear　vibration　partial　differential　equation　is　first　discretized　to　become　an　ordinary　differential　equation　by　applying　the　Galerkin　method.　The　main　resonance　modulation　equations　and　the　parametric　resonance　for　the　external　excitation　frequency　that　is　close　to　the　system＇s　second-order　modal　frequency　are　then　obtained　by　using　the　multiscale　method.　The　Newton-Raphson　method　is　subsequently　applied　to　obtain　the　bifurcation　diagram　of　the　steady-state　equilibrium　of　modulation　equation　with　varying　system　parameters.　The　equilibrium　stability　is　finally　analyzed.　We　confirm　the　existence　of　static　bifurcation　such　as　saddle-node　bifurcation,　pitchfork　bifurcation,　and　Hopf　dynamic　bifurcation.　A　detailed　analysis　is　also　conducted　on　the　complex　nonlinear　jump　phenomenon　caused　by　the　presence　of　multiple　nonlinear　steady-state　solution　regions.　In　the　dynamic　Hopf　bifurcation　interval,　the　fourth-order　Runge-Kutta　method　is　used　to　continue　to　track　the　dynamic　periodic　solution　of　the　modulation　equation　in　Cartesian　coordinates.　It　is　found　that　there　are　multiple　boundary　crises　and　attractor　merging　crises　in　the　vibration　system　for　piezoelectric　composite　lattice　sandwich　plates.