The postbuckling behavior of stiffened composite cylindrical panels was studied analytically and experimentally. Progressive failure analysis was implemented for the prediction of failure characteristics and postbuckling ultimate load. For the progressive failure analysis, the maximum stress criterion is applied to the average stress in each layer of all the finite elements. Using the same degenerated three dimensional isoparametric solid element in order to model stiffeners and the skin, the global and the local buckling of the stiffened panel can be depicted exactly. The results show the effects of stiffener location, and various stiffener heights and thickness on the postbuckling behavior of stiffened composite cylindrical panels. The postbuckling ultimate load of stringer-stiffened composite cylindrical panel is not dependent of the initial buckling load, but becomes higher as the stiffener thickness and height increase.