Abstarct: The effect of crack on load-bearing capacity and buckling behavior of cylindrical panel is an essential consideration in their design. In this paper, experimental and numerical buckling analysis of steel cylindrical panel of various lengths and diameters with crack have been studied using the finite element method and the effect of crack position, crack orientation and the crack length-to-cylindrical shell perimeter (λ=a/2πr) and shell length-to-diameter (L/D) ratios on the buckling and post-buckling behavior of cylindrical shells has been investigated. For several specimens, buckling test was performed using an INSTRON 8802 servo hydraulic machine and the results of experimental tests were compared to numerical results. A very good correlation was observed between numerical simulation and experimental results. Finally, baxsed on the experimental and numerical results, sensitivity of the buckling load to the shell length, crack length and orientation has also been investigated.