Abstract: Functionally graded material has complex microstructures, and its internal structure is more complicated than the homogeneous material’s. Therefore, the analytic solution for dynamic analyses of functionally graded structure is difficult to obtain. A new microelement method for the dynamic analyses of functionally graded structures was suggested to establish quantitative relation between the macro-character and microstructures of functionally graded materials, and the mechanism, that different combination and variation of materials have different macro-character, can be founded. This microelement method can fully realize the transition from material micro-constitution to macro-response of structure, and its computational elements and degrees of freedom are the same as that of the normal finite element method. Moreover, in this method, any microconstitutions of functionally graded materials will be reflected without increasing the degrees of freedom. In this paper, the three-dimensional dynamic characters of functionally graded plates with different medium components net structures are analyzed, and the three-dimensional dimensionless values of natural frequencies and the three-dimensional distributions of mode shapes of the functionally graded plates are given. Especially, the stress modes in the plane contour charts of functionally graded plates with different medium components net structures are compared in this paper. The results show that micro-net structures have great influences on the three-dimensional dynamic response of functionally graded structures.