Abstract: Composite stiffened panel is typical structural form, which is widely used in aircraft wing, tail, and fuselage structures. When suffering aerodynamic loading, such composite stiffened panel on the wing surface of the wing is under compressive pressure, and this pressure could cause such panel to buckle or even failure. In this paper, an engineering method of reasonably predicting the buckling load of composite stiffened panels under axial compression is proposed, according to previous research on the stability engineering method composite stiffened panels under axial compression and stability engineering method of metal stiffened panels under axial compression which has been maturely applied in engineering. Therefore, two kinds of reinforcement composite stiffened panels (i.e., three types of Y type and two types of J type) are considered. The axial buckling load of the example is calculated by using the engineering method proposed in this paper, and the finite element numerical simulation and test verification are carried out. Compared with the experimental results, the relative error of the engineering method is less than 10%. Compared with the finite element calculation results, the relative errors of the other configurations are 5% except for one Y-shaped truss stiffened panel which is 10%, which meets the engineering requirements and proves the effectiveness of this method. This engineering method has been applied in the development of model aircraft. In addition, it is found that the weakening of the stringer edge of the stiffened panel will reduce the buckling load of the composite stiffened panel, and the weakening of the middle two stringers of the Y-stiffened panel can make the stringers more match the stiffness of the skin, and improve the failure strain level of the Y-stiffened panel.