Corrugated sheets made of metal have been widely utilized so far. Analysis for these structures is significant. In this study, the analysis of natural vibration of sinusoidal corrugated metal plats will be conducted. Instead of determining the natural vibration frequencies directly from the real sinusoidal corrugated plate, the results can be gotten from the equivalent orthogonal plates by analytical method. This is due to the fact that the origin is equivalently considered as a thin plate with uniform thickness and both membrane stiffness and flexural stiffness are transferred to those of equivalent plate. The analytical results obtained by the proposed models will be compared with those is directly received in the real sinusoidal corrugated plate by finite element method (ANSYS). Two boundary conditions considered are simple supported and clamped four edges. The results reveal that the relative errors of natural vibration frequencies between two methods are small. The maximum error percentage of 3.23% occurring at the seventh mode of the simply supported boundary condition. It can be concluded that the utilization of the equivalent orthogonal model of the real plate can reduce the computing time. Moreover, this proposed model can be widely the folded plate in form of trapezoidal shape made metal of composite materials, as well as the static, dynamic problems with various boundary conditions.