Abstract: A strength analysis model was presented to study the progressive damage of integral stiffened composite panels subjected to compressive loading by using the nonlinear finite element method. In the model, the debonding failure of the adhesive between the skin and stiffener was considered by adding cohesive elements between the shell elements. Quads failure criteria and Hashin’s failure criteria were adopted to identify the occurring of damage events of the cohesive elements and the composite panels, respectively. Based on ABAQUS, a material degradation rule containing continuum damage status variables was presented.The process of damage initiation, propagation and catastrophic failure of the integral stiffened composite panels was simulated in detail by the proposed model, and the initial geometric imperfection was taken into account. Axial stiffness ratio of stiffener and skin was defined and conducted to study the effects to the structure on the carrying capacity and failure modes. The results indicate that: the model can predict the damage process of integral stiffened panel effectively; under the condition the ply design is reasonable, increasing the stiffness ratio can to some extent improve the unit area bearing capacity of the cross section of stiffened composite panels.