Nonlinear　dynamic　behaviors　of　a　simply　supported　3D-Kagome　truss　core　sandwich　plate　subjected　to　the　transverse　and　the　in-plane　excitations　are　investigated　in　this　paper.　The　truss　core　sandwich　plate　is　equivalent　to　a　laminated　plate　with　three　laminas　according　to　the　equivalent　sandwich　plate　method.　The　governing　equation　of　motion　for　the　truss　core　sandwich　plate　is　derived　by　using　the　von　Karman　type　equation　for　the　geometric　nonlinearity　and　the　Reddy＇s　third-order　shear　deformation　plate　theory.　The　nonlinear　governing　partial　differential　equation　is　reduced　to　the　ordinary　differential　equation　by　applying　the　Galerkin＇s　approach.　The　four-dimensional　averaged　equation　is　obtained　by　using　the　method　of　multiple　scales.　The　frequency-response　curves　are　obtained　under　consideration　of　strongly　coupled　of　two　modes.　The　results　indicate　that　there　are　the　hardening　and　softening　nonlinearities　in　the　truss　core　sandwich　plate　under　the　specific　resonant　case.　The　influences　of　the　amplitudes　for　the　in-plane　and　transverse　excitations　on　the　frequency-response　curves　are　investigated.　The　results　of　numerical　simulations　for　the　two-degree-of-freedom　nonlinear　equation　exhibit　the　existence　of　the　period,　multi-period　and　chaotic　responses　with　the　variation　of　the　excitations,　which　demonstrate　that　those　motions　appear　alternately.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.