Due to high strength and stiffness-to-weight ratio of composite cylindrical shells, they are increasingly being used in different industries. Applying different types of stiffeners is one of the ways to improve the buckling resistance of these structures. In this paper new analytical method based on smear method is developed to analyze the stiffened composite shells. The main difference of this method and previous methods is on technique of combination of shell`s and stiffeners` stiffness parameters, and calculating the equivalent stiffness parameters. In the suggested method a three layered shell is designed in such a way that this shell and stiffeners have the same volume and stiffness. Putting these layers under the main layers of shell, the equivalent stiffness parameters could be calculated easily. Using the Ritz energy method the critical load of axial buckling of shell is calculated. The method is verified using finite element ABAQUS package. The results show that the proposed method has less difference from finite element`s results compare to previous methods. In addition, the effects of different parameters on buckling load and special buckling load of stiffened shell is investigated. The results show that in order to have efficient stiffened structure; there must be an adequate number of ribs and unit cells. It also shows that, although adding stiffening ribs increase the buckling load of the shell, the special buckling load does not increase necessarily. The optimum angle for helical ribs is 30 to 40 degrees respect to axis of the cylindrical shell.