Due to the increasing need for various materials of different properties, nowadays the use of nanomaterial’s including Nano composites has been developed in the industry. These composites consist of two phases. The first phase, called the matrix and the second phase is composed of Nano-scale morphologies. Good mechanical and thermal properties of these materials could have important effects on the composite strength. Among the Nano-materials, Carbon nanotubes are noticeable. They have an elastic modulus about 1TPa (one Tera Pascal) which are of the highest moduli of elasticity among the materials. Because of lower resistance of the matrix phase relative to the reinforced phase, when the plate undergoes different loads, the loads are transferred to the reinforcement phase. Due to the remarkable mechanical properties of nanotubes, composite plate will show a greater resistance. In this thesis, buckling analysis of plates reinforced with carbon nanotubes has been investigated. To obtain the elastic modulus of the composite plate, Mori -Tanaka theory has been employed. This theory is an analytical method to obtain the internal stress of composite plate. According to the experimental researches, composite plates in which Nanotubes are randomly distributed have better resistance under different loads. In this thesis for the first time, buckling analysis of thin and moderately thick plates reinforced with randomly distributed ingle-walled carbon nanotubes has been investigated. Also, due to the growing needs of industry with various forms of the plate and the complications of the analysis of this type of plate, buckling analysis of thin and moderately thick parallelogram plates is discussed. For the buckling analysis of plates with square, rectangular or parallelogram forms under in plane loads and different boundary condition, the spline finite strip method has been used. For mapping of parallelogram plate to the rectangular plate, spline finite strip method is employed. Then by solving the eigenvalue problem, critical loads and local buckling coefficients are obtained which can be used in designing of plates with different shapes and boundary conditions. It has been shown that increasing the volume fraction of carbon nanotubes in the composite plate, stiffness and critical load of the composite are increased.