Stiffened panel is a typical strength member in ships. Considering the change of material properties under the action of fire and high temperature, according to the thermal elastic-plastic finite element theory, based on the nominal temperature-time curve, the protective effect of the passive fire protection layer on the high temperature response characteristics and the residual strength of the stiffened panel and the influence of coating positions on the failure mode of the stiffened panel are studied, which provides reference for structural performance evaluation and structural fire protection design. Numerical analyses indicate that passive fire protection layer can effectively slow down the increase of stress and deformation induced by temperature rise. Overall coating does not change the failure mode of the overall buckling of the structure accompanied by the tripping of the stiffener, but significantly delays the failure time and has an obvious effect on maintaining residual ultimate strength. Partial coating will change the failure characteristics of the structure. Overall failure occurs when only the plate is coated, and beam-column failure occurs when only the stiffener is coated, accompanied by local buckling of the web. Overall coating shows the best protective performance on the residual strength of the stiffened panel, followed by plate coating. Stiffener coating, however, has a weak protective effect. The protection performance mainly depends on the heating and failure mode of the structure.