Abstract: This paper focuses on the Process Integration and Design Optimization (PIDO) technique in the design of composite materials to improve the structure stiffness, taking the widely-used carbon fiber reinforced polymer (CFRP) in the field of aircraft as an example. Calculation is based on the composite structure of the laminate, and aims at maximizing the intrinsic frequency of the structure. By adjusting the thickness and layout angle of laminate in composite material plate, the optimization results could be obtained from the simulation of angle change by the finite element numerical method. The frequency of the structure can be used as the optimization objective, and the results are judged by the optimization algorithm. Finally, this strategy provides a better optimization which improves the stiffness of the structure and reduces the weight, by compare two PIDO optimization process, more method for the optimization design can be provided.