In order to improve the accuracy of local buckling engineering method of hat-stiffened composite panel, the stability experiment of typical panels under axial compression was first carried out, and then an updating engineering method for local buckling of hat-stiffened composite panel based on flexural stiffness ratio was proposed. The predicted buckling loads differ less than 3% from experimental results. The buckling analysis of two kinds of hat-stiffened panels with bottom flange was carried out by finite element model (FEM) method and the updating method this paper proposed comparatively. The error of compared results is within 10%, which verifies the reasonableness of the proposed method and satisfies the engineering accuracy. Experimental data recorded in public literature were analyzed by engineering simplified method, energy method and the updating method this paper proposed comparatively. Results show that the error by engineering simply and fixedly supported boundary conditions can be reduced from 41.5% and 5.3% to 3.8% respectively, which provides a new rapid analytical method for preliminary design of hat-stiffened composite panel.