With both analytical and numerical methods, chaotic motions of a clamped thin circular elastic plate in coupling fields are investigated in this paper. The chaotic motions arising from the transverse intersections of the stable and unstable manifolds of the heteroclinic orbits are analyzed by means of Melnikov method. The critical curves separating the chaotic and non-chaotic regions are obtained. The chaotic feature on the system parameters are discussed in detail. Some new dynamical phenomena are presented. Numerical simulations are also given, which verify the analytical results.