Abstract: On the basis of the first order shear deformation theory, a nonlinear finite element analysis method has been developed to study the thermal buckling behavior of delaminated advanced composite grid plates. The temperature dependent thermal and mechanical properties of the composite were considered and a constrained model was established to ensure deformation compatibility between sub-laminates in the front of the delamination. Comparing the thermal critical temperature and buckling modes of the bare and single direction stiffened laminates with those of advanced grid stiffened laminates (AGS), the result shows that the advanced grid composite laminates possess stronger thermal bucking resistance; however thermal critical temperature values are reduced and the corresponding buckling modes are also changed with increasing the delamination area. The methods and conclusions provided have the reference value for composite structure designers in load capacity prediction and damage tolerance design of AGS.