Abstract: [Objectives] In order to accurately assess the ultimate load carrying performance of the hull structure under cyclic loading, it is necessary to consider the effect of cyclic properties of the load on the ultimate strength of the hull stiffened plate. [Methods] The finite element software ANSYS was used to carry out the numerical simulation of ultimate strength based on elastic shakedown state under in-plane cyclic loading for 200 T-bar stiffened plates and flat-bar stiffened plates. The material Bauschinger effect, initial welding deformation and residual stresses of the hull stiffened plate under in-plane cyclic loading were considered in detail. [Results] Based on the results of the nonlinear finite element numerical simulation of the “upper” and “lower” limits of the elastic shakedown critical state of the stiffened plate. With the dimensionless ultimate strength of the stiffened plate as the objective function and the flexibility coefficients of the plate and stiffened plate as the independent variables, the prediction equation of the ultimate strength of the stiffened plate based on the elastic shakedown critical state under in-plane cyclic loading is proposed. [Conclusions] The accuracy of the formulation is verified by comparing it with the results of nonlinear finite element analysis. The work done in this study has good theoretical and engineering significance for the ultimate strength assessment of hull stiffened plates under cyclic loading.