Abstract: A finite element model based on Mindlin's theory is used for the geometriclly nonlinear analysis of laminated stiffened plate.Using the total Lagrangian description the incremental equations and nonlinear stiffness matrix of the isoparametric stiffened plate element are formulated.The Newton-Raphson iteration procedure combined with the increment method is employed to trace the nonlinear equilibrium path.A variety of numerical examples are presented to demonstrate the precision and convergence of the method.All the results have a good agreement with those published.The effects of bounday condition,the size of transverse area of stiffener,the distribution of stiffener and the orientation angle of lamina on the geometricaly nonlinear strength of stiffened composite plates are investieated.