This paper presents a finite element analysis of the geometrically nonlinear and stability behaviours of composite layered plates using a high-order facetted shell element. Element equations are derived based on Reissner theory and, the lateral deflection is modelled using Conforming or Non-conforming Hermition shape functions. Green's strain equations are used to represent nonlinear terms associated with geometrical nonlinearity. To avoid the unsymmetry problem of the stiffness matrix due to large deformation effect, the part of the stiffness equation dealing with the large deformation effect is represented separately as a force vector. A programming package based on the developed element was designed. Several case studies nave been investigated and package results were compared with published theoretical and/or experimental results. The effect of some effective parameters on the behaviour of the composite plates has been investigated with some case studies, and the results have proved that the developed package can be useful tool for the optimisation of composite layered plate structure.