Abstract: The paper used analytical method to deal with the stability problem of stiffened plates, by ignoring the influence of material＇s nonlinearity, it employed theoretical method to resolve critical buckling stress of stiffened rectangular plate with simplified supporting. For single stiffened plate, the deflection function was defined and introduced to boundary equation and coordinate equation, which acquired the critical stress of stiffened plate by solving linear equations. For plate with two or more stiffeners, the paper acquired the critical stress through uniform formulation using Energy Method. The results of numerical simulation by using Abacus and Nast ran were compared with theoretical solutions, the validity of analytical method was verified, it can be used to solve the stability problem of stiffened plates.