This paper describes a perturbation technique to perform the nonlinear response analysis of plate structure under random acoustic excitation. In the analysis, use is made of triangular plate element together with a nonlinear plate stiffness element which is dependent on the modal response of the structure. The nonlinear plate stiffness element
represents the coupling term between the membrane and bending deformation. Applying these elements and the associated consistent mass matrices, the equivalent linear eigen matrix of the complete plate is organized. The eigen solution and the following modal spectral computation completes the iteration cycle. A flow diagram and a numerical example are included which illustrate the application of the method to practical problems.