Abstract: Based on progressive damage theory, a non-linear and multi-scale damage model is developed to consider the stiffness reduction caused by micro-crack before the failure of a single lamina. The Hoffman criterion is taken as an ultimate condition for the damage to a single lamina of composite laminate in complex stress state. Then, the criterion is introduced to a numerical analysis made for the damaging failure process of a composite laminate with a hole under unilateral load, and the result of the analysis is compared with that taking conventional or no damage failure criterion. The results indicate that the stress concentration is relaxed due to the reduced stiffness of damaged single lamina which leads the stress to redistribute and accelerates the stress transfer to undamaged laminae and their peripheral elements. It implies that the failure load of a single lamina is improved greatly as well as the ultimate load of the composite laminate. But, the way to laminate will affect the improvability. The analysis reveals that the decreasing stiffness due to damage should be taken into account in the failure analysis of composite laminates.