Abstract: For the strength design and analysis predictions of a composite structure, a continuum stiffness degradation model is proposed based on Tsai-Wu failure criterion, and the general progressive failure analysis methods for both the laminated and bulk composite structures are established. The user material subroutines of ABAQUS are programmed. With the new subroutines, the numerical simulation of typical laminated and bulk composite components, as well as their test verification analyses are carried out. It shows that the new theoretical model with its algorithm can provide higher accuracy and better simulation ability than the method for state-of-art composite laminates. Meanwhile, the relative error of predicted ultimate strength for a typical C/C bulk composite component can meet the level of 20%.