Abstract: the main failure mode of composite stiffened panel is buckling. In order to ensure the safety of the structure and effectively reduce the weight of the structure, it is necessary to systematically study the boundary conditions and the width of the load-bearing edge of the skin when checking the buckling. Through the study of two kinds of boundary conditions and three kinds of skin load edge width selection, a method of skin load edge width selection considering the influence of stringer is put forward to calculate the buckling of stiffened panel and verify with the test results. The research results show that the engineering buckling calculation method with the boundary conditions of four sides simply supported and the width of the loading edge of the skin considering the influence of the stringer has the highest accuracy, the minimum deviation between the calculation results and the test results is 0.29%, the maximum deviation is 7.16%, and all of them are lower than the test values. It is safe and reliable to use this method to check the strength and stability of structures. Key words:composite;stiffened panel;buckling;engineering calculation method.