The　free　vibration　of　composite　truss　core　sandwich　plates　is　investigated.　The　natural　frequencies　of　the　sandwich　plate　are　calculated　by　using　the　classic　laminated　plate　theory,　the　first-order　shear　deformation　theory,　Reddy＇s　third-order　shear　deformation　theory,　and　a　Zig-Zag　theory.　The　differences　between　the　natural　frequencies,　obtained　from　the　four　theories,　are　compared.　The　influences　of　structural　parameters　on　the　natural　frequencies　and　the　ratios　of　natural　frequency　to　equivalent　density　of　the　sandwich　plates　with　pyramidal　core,　tetrahedral　core,　and　3D-Kagome　core　are　studied　with　the　aid　of　the　Zig-Zag　theory.