In　this　paper,　an　extended　high-dimensional　Melnikov　method　is　used　to　investigate　global　and　chaotic　dynamics　of　a　simply　supported　3D-kagome　truss　core　sandwich　plate　subjected　to　the　transverse　and　the　in-plane　excitations.　Based　on　the　motion　equation　derived　by　Zhang　and　the　method　of　multiple　scales,　the　averaged　equation　is　obtained　for　the　case　of　principal　parametric　resonance　and　1:2　sub-harmonic　resonance　for　the　first-order　mode　and　primary　resonance　for　the　second-order　mode.　From　the　averaged　equation　obtained,　the　system　is　simplified　to　a　three　order　standard　form　with　a　double　zero　and　a　pair　of　pure　imaginary　eigenvalues　by　using　the　theory　of　normal　form.　Then,　the　extended　Melnikov　method　is　utilized　to　investigate　the　Shilnikov-type　multi-pulse　heteroclinic　bifurcations　and　existence　of　chaos.　The　analysis　of　the　extended　Melnikov　method　demonstrates　that　there　exist　the　Shilnikov-type　multi-pulse　heteroclinic　bifurcations　and　chaos　in　the　four-dimensional　non-autonomous　nonlinear　system.　Finally,　the　results　of　numerical　simulations　also　show　that　for　the　nonlinear　system　of　simply　supported　3D-kagome　truss　core　sandwich　plate　with　the　transverse　and　the　in-plane　excitations,　the　Shilnikov-type　multi-pulse　motion　of　chaos　can　happen　and　further　verify　the　result　of　theoretical　analysis.