In　this　work,　thermal　buckling　and　postbuckling　behaviors　of　graphene　platelet　(GPL)　reinforced　porous　nano　composite　beams　are　studied　with　inclusion　of　temperature-dependent　material　properties　for　the　first　time.　The　Halpin-Tsai　micromechanics　model　and　extended　rule　of　mixture　as　well　as　open-cell　metal　foam　model　are　applied　to　determine　the　effective　properties　of　nanocomposites.　A　high　order　shear　deformation　theory　with　the　aid　of　von　Karman　nonlinearity　is　implemented　to　yield　governing　equations　corresponding　to　thermal　buckling　and　postbuckling　problems.　The　numerically　stable　admissible　functions　constructed　through　Gram-Schmidt　procedure　are　developed　to　describe　end　restraints　of　beams.　An　eigenvalue　equation　without　geometric　nonlinearity　is　solved　to　obtain　critical　buckling　temperatures,　while　an　iterative　methodology　is　implemented　to　find　the　temperature-dependent　thermal　postbuckling　paths　of　beams.　An　extensive　numerical　study　is　performed　to　check　the　influences　of　internal　pores　and　GPL　reinforcements　on　the　thermal　buckling　and　postbuckling　responses　of　GPL-reinforced　metal　foam　beams.　It　is　found　that　the　temperature-dependency　of　material　properties　plays　important　roles　on　thermal　buckling/postbuckling　behaviors　of　GPL-reinforced　porous　beams,　and　dispersing　more　GPLs　on　the　upper　and　lower　surfaces　and　fabricating　more　internal　pores　near　central　portion　of　beams　can　improve　thermal　instability-resistance　capability　of　composite　structures.