This　paper　studies　the　global　bifurcations　and　multipulse　chaotic　dynamics　of　a　four-edge　simply　supported　honeycomb　sandwich　rectangular　plate　under　combined　in-plane　and　transverse　excitations.　Based　on　the　von　Karman　type　equation　for　the　geometric　nonlinearity　and　Reddy＇s　third-order　shear　deformation　theory,　the　governing　equations　of　motion　are　derived　for　the　four-edge　simply　supported　honeycomb　sandwich　rectangular　plate.　The　Galerkin　method　is　employed　to　discretize　the　partial　differential　equations　of　motion　to　a　three-degree-of-freedom　nonlinear　system.　The　six-dimensional　nonautonomous　nonlinear　system　is　simplified　to　a　three-order　standard　form　by　using　the　normal　form　method.　The　extended　Melnikov　method　is　improved　to　investigate　the　six-dimensional　nonautonomous　nonlinear　dynamical　system　in　a　mixed　coordinate.　The　global　bifurcations　and　multipulse　chaotic　dynamics　of　the　four-edge　simply　supported　honeycomb　sandwich　rectangular　plate　are　studied　by　using　the　improved　extended　Melnikov　method.　The　multipulse　chaotic　motions　of　the　system　are　found　by　using　numerical　simulation,　which　further　verifies　the　result　of　theoretical　analysis.