Abstarct: In this thesis, Optimization of buckling of square composite plates with different cutouts under thermal loading using genetic algorithm was investigated. Loading as uniform temperature rise applies to the entire plate. The material plate is hybrid composites of four laxyers of Glass / Epoxy and Boron / Epoxy. The cutout studied in this research consists of circular, quasi-triangular, quasi-square, pentagonal, and hexagonal located in the center of the plate. The solving method used to analyze this thesis is the finite element baxsed on the energy method. Also, the theory used in this thesis is the first-order shear deformation theory. In the continue, the optimal values of effective parameters on buckling are obtained in order to achieve the maximum critical buckling temperature using the genetic algorithm. In the genetic algorithm, the critical buckling temperature is considered as objective function. The effective parameters on the thermal buckling that have been optimized in this thesis include bluntness of cutout corners, cutout orientation, fiber angle and cutout size to plate size ratio. Also, the effect of different boundary conditions and various stacking sequences of composite laxyers on critical buckling temperature has been investigated. According to the results, it can be seen that, contrary to expectation, the circular cutout is not the best geometry for increasing plate resistance against thermal buckling and in some cases, with the proper selection of bluntness of cutout corners and the angle of cutout orientation, the critical buckling temperature can be increased in comparison with the circular cutout. Also, with proper selection of stacking sequences, the plate's resistance to thermal buckling can be greatly increased.