The paper presents a mechanical analysis of the multi-layer circular composite plate For MEMS devices. Each layer of the plate is assumed to have different radius, material properties and initial stresses. Governing equations for the composite plate are derived based on the classical laminated plate theory, and analytical soultions have been developed for static deflection of the initially stressed plate due to transverse pressure loading as well as for a given electric field in the piezoelectric layer. A nonlinear finite elernent analysis of the plate is also performed. The analytical result match the FE results for the range of parameters used in the microphone design. The analytical model will be useful in the design and optimization of MEMS devices containing circular piezoelectric composite plates and diaphragms.