A composite stiffened panels configuration design method is proposed integrating various mechanical simplified models, dealing with global and local buckle separately based on two-level optimization framework.An equivalent stiffness model is constructed for airframes unidirectional stiffened panel with complex sections, optimizing stiffness match relationships from global perspective in system level.Critical buckling load of skin is fitted by nonlinear rational interpolating function surrogate model, which handles local buckling in subsystem level, optimizing the layout and detail dimensions according to the stiffness requirements from system level.An integrated framework is built based on collaborative optimization theories to coordinate and unify each levels critical load to improve material utilizing, and the panels integrated design could be implemented.Finally, the layout optimization of a panel with Z stringers is processed.Calculation result satisfies the design requirements, and every optimization level shows a high precision, which validates the reliability of this method.