Based on the buckling strength of food stiffened plate as the breakthrough point, this study explores the elastic-plastic stability and conducts the stability series analysis of food stiffened plate by virtue of the analysis of longitudinal in-plane load and lateral pressure load of the food stiffened plate frame. The stress state of the food stiffened plate structure is very complex, which is subject to not only the longitudinal pressure caused by the longitudinal bending, but also the lateral pressure of the water. Therefore, it is necessary to consider the full load suffered, in order to calculate the buckling strength of stiffened plate more accurately.