The paper is concerned with a finite element model to predict the ultimate load and behaviour of stiffened plates subjected to lateral pressure and in-plane loading. The stiffened plates considered are all simply supported along the four edges. A finite element package ABAQUS is used to simulate the behaviour of stiffened plates. Initial imperfection of stiffened plates is taken into account in the finite element analysis. Accuracy of finite element analysis is assessed by comparing ultimate load and failure shape with experimental results from other researchers. Comparison shows that the finite element method is able to predict accurately both the behaviour and ultimate load of stiffened plates.