In　this　paper,　the　propagation　of　guided　thermoelastic　waves　in　laminated　orthotropic　plates　subjected　to　stress-free,　isothermal　boundary　conditions　is　investigated　in　the　context　of　the　Green-Naghdi　(GN)　generalized　thermoelastic　theory　(without　energy　dissipation).　The　coupled　wave　equations　and　heat　conduction　equation　are　solved　by　the　Legendre　orthogonal　polynomial　series　expansion　approach.　The　validity　of　the　method　is　confirmed　through　a　comparison.　The　dispersion　curves　of　thermal　modes　and　elastic　modes　are　illustrated　simultaneously.　Dispersion　curves　of　the　corresponding　pure　elastic　plate　are　also　shown　to　analyze　the　influence　of　the　thermoelasticity　on　elastic　modes.　The　displacement　and　temperature　distributions　are　shown　to　discuss　the　differences　between　the　elastic　modes　and　thermal　modes.