To research the strength of composite material barrels, based on the CDM theory, an energy-based stiffness degradation method is proposed to predict the progressive failure properties of steel- fiberglass/ epoxy composite laminated barrels. Three failure modes of fiberglass/ epoxy composites, including fiber breakage, matrix cracking and fiber/matrix interface shear failure are considered in the present model. A 3D finite element technique including the multiframe restart analysis is employed to conduct the progressive failure analysis. The results indicate that the mode considering the stiffness degradation and progressive failure of the material is more reasonable on researching the strength of composite material barrels. The strength of composite material barrels in this paper is influenced by the fiber strength mainly.