Abstract: A method dealing with stacking sequence optimization of composite stiffened panel considering buckling was proposed. Based on the energy-based method in calculating buckling loads of composite stiffened panels, the explicit formulations in calculating local buckling loads of skin and stiffener of composite stiffened panel were proposed systematically. The influences of each elastic supporting panel element and stiffener’s foot were taken into account during the calculation of the local buckling loads of skin and stiffener. Engineering method was introduced to calculate the global buckling load. Based on the homemade HAJIF’s composite stacking engineering library, the stacking parameters were regarded as design variables and the proposed explicit formulations in calculating buckling loads were used to build an optimization progress of composite stiffened panels’ stacking sequence and its program implementation. The least square method was applied to choose the most closed staking parameter of optimized and engineering-library laminates automatically. A higher accuracy and efficiency of the proposed formulations in calculating the buckling loads of composite stiffened panels was obtained in comparison with the traditional FEA method. The numerical optimization examples of the composite stiffened panel show that the stiffened panel’s buckling load increases by 17% with an almost unchanged weight. And the optimal stacking sequence results can be extracted from the composite stacking engineering library and be used in practical structure directly.