Abstract: In this paper,the nonlinear transverse deflection or buckling is analyzed for unsymmetrical composite laminates under loads in plane by means of the generalized Fourier series method.The influences are studied mainly of the layout of unsymmetrical laminates and the type of loads in plane on the transverse deflection of composite laminates supported simply at four edges.The curves of load-transverse deflection or the curves of pastbuckling equilibrium inspecial case of composite laurinates are obtained by solving the nonlinear governing equations. The numerical result show that the unsymmetrical composite laminates under loads in plane generally produce only transverse deflection,but not buckling