Based on the continuum damage mechanics, this paper established a 3D laminates model with a large opening under shear loading ,calculated the ultimate strength and simulated the damage process. The numerical results were compared with the relevant experimental study and demonstrated the feasibility of this method. Then ,the paper established a finite element model of an aircraft porthole structure to study the mechanical behavior under pure shear load of composite material containing reinforcing frame structure with a large opening and analyzed the damage law.