Abstract:A finite element model for inertial navigation structure of the mechanically dithered ring laser gyroscope was established based on its physics structure. The structure’s natural frequencies and modals were calculated utilizing ANSYS software. The results of modal analysis and experimental measurements were compared. It proves that the results of the modal analysis and experiments measurement were consistent and the errors of the finite element analysis were no more than 5.23%, so that the finite element analysis was effective and efficient. The weakness of the present structure was indicated. The results obtained are helpful for improving the dynamic modification and optimum design of the inertial navigation structure of the mechanically dithered ring laser gyroscope.