Abstract: Nonlinear FEM has been performed to a series of two-way orthogonal multi-stiffened plates subjected to axial compression load. Based on numerical results and orthotropic plate theory，we introduced three parameters，which were longitudinal column slenderness ratio λx ，transverse column slenderness ratio λy ，and plate slenderness ratio β ，to form a prediction formula to calculate the ultimate strength of two-way orthogonal multi-stiffened plates. Then the ultimate strength for three types of multi-stiffened plates was analyzed. The results show that the calculation data agree well with the results of finite element analysis，and the proposed prediction formula is able to accurately predict the ultimate of two-way orthogonal multi-stiffened plates.