One of the main problems of cylindrical structures is their sensitivity to buckling. In this study, the buckling behavior of stiffened cylinders is investigated. Three types of cylindrical shell, namely, unstiffened-cylinder shell, stringer-stiffened cylinder shell, and ring-stiffened cylinder shell, were developed with a geometrical-variations. The numerical benchmark has been confirmed experimental works from published references. The Finite Element Analysis (FEA) was carried out using the ABAQUS. Imperfection in this study was considered. The load in this study uses external pressure. The cylinder shell diameter used in this simulation is 711.2 mm, 762 mm, and 812.8 mm. Failure in the cylinder is usually in the form of dents and can spread along with the cylinder shell, which can be referred to as cylinder propagating. The addition of the stiffener increases the buckling capacity of the cylinder shell.