Abstarct: In this thesis, the effect of dispersion nano clays in to the matrix material and the use of glass fibers in the fabrication of composite sandwich panels on buckling and vibration behavior as well as changes in the type of core have been investigated. Sandwich beams have a rectangular cross section and are subjected to axial compressive load. samples of composite sandwiches are made of foam core and composite surfaces. Also, the composite surface material is composed of three laxyers of glass/epoxy fibers. The purpose of this experiment is to investigate the maximum critical buckling load, maximum energy absorption and the study of natural frequencies in composite sandwich beam samples. Samples are made with simple core and zigzag core and 0, 3, 5 and 7 weight percentages of nano clays. The results of the axial compressive load in fixed-fixed conditions show that the addition of nano clay improves energy absorption and also improves the critical buckling load. The results show that by adding 3 percent by weight of nano clay, the critical buckling load of composite sandwich column has increased by 25%. Also, the critical buckling load containing 7 percent by weight of nano clay has increased by 27%. The images from the SEM show that in the sample 3 percent and 7 percent by weight, the nanoparticles are well dispersed in the matrix, and as a result, the accumulation of nanoparticles has rarely occurred. The results of forced vibrations of sandwich composite beams in fixed-free conditions showed that the natural frequency of the first mode of the sample with zigzag core increased by 16% compared to the sample with simple mode core. it can be concluded that this increase in the zigzag core occurred due to the greater adhesion between the core and the surface. Among the different percentages of nanoparticles in the zigzag sandwich beam, the 3 percent by weight nano clay sample decreased by 6%, the 5 percent by weight sample decreased by 1% and the 7 percent sample increased by 4.5%. Also, for verification of laboratory results, a sample of composite sandwich beam with simple core and epoxy glass fiber surface has been simulated in Abaqus finite element software.