A model of multi-parallel-beam joined with single-beam is adopted in the theoretical analysis of the natural vibration characteristics of the parallel-plate assembly. In the study of theoretical calculation and analysis of the wet-modal natural frequencies and modes, the dry-modal mode functions are used as trial functions to solve the complex-modal mode equation by variational method. In the study of stability of the parallel-plate assembly, its critical flow velocity and destabilizing deflection are analyzed and calculated by direct method and variational method, and the results of the two m...