A method of systematic modeling was presented to analyze dynamic characteristics of an assembled thin plates structure. Based on dynamic fundamental solutions of a thin plate, governing boundary equations in the lateral and internal vibration of the thin plate are established by using a boundary element method (BEM). According to assembled conditions on the boundary, dynamic characteristics equations of the assembled thin plates structure are deduced. In order to raise calculating efficiency and avoid complicated programming operation, an approach of frequency scanning is introduced to analyze dynamic characteristics of the assembled thin plates structure. The natural frequencies and modal shapes are obtained fast and effectively. By numerical calculation and experiments given, the established method has not only good precision but also high efficiency.