In　this　study,　we　investigated　the　nonlinear　thermally　induced　transient　response　of　lattice　core　sandwich　plates　under　the　sudden　application　of　heat　flux　for　the　first　time.　First,　the　equivalent　thermal　conductivity　of　the　lattice　core　sandwich　plates　is　obtained　by　considering　the　thermal　conduction　within　the　trusses　and　heat　ra-diation　in　the　cells.　The　one-dimensional　transient　heat　transfer　equation　was　implemented　and　solved　using　the　central　finite　difference　method　to　calculate　the　transient　temperature　field　along　the　direction　of　the　thickness　of　the　plate.　The　displacement　fields　of　the　facesheets　and　lattice　core　layer　were　modeled　using　the　Kirchhoff　plate　theory　and　the　first-order　shear　deformation　theory,　respectively.　Based　on　the　Lagrange　method　and　the　assumed　modal　method,　the　governing　equations,　with　mechanical-thermal　coupling,　for　the　simply　supported　lattice　core　sandwich　plates　under　sudden　heat　flux　are　derived.　Through　a　series　of　examples,　the　influences　of　the　different　lattice　core　cell　types,　thermal　boundary　conditions,　truss　radii,　and　cavity　heat　radiation　on　the　nonlinear　thermally　induced　transient　responses　of　the　sandwich　plates　are　explored.