Abstract: Based on the design of frame-type bracket, the triaxial integration and optical multiplexing technique were used to accomplish the light-weight design of triaxial integrated fiber-optic gyroscope (FOG) through the optical-component miniaturization and multichannel-integration of gyroscope-signalprocessing circuits. The influence of the bracket wall thickness together with the mounting-interface dimension of fiber-ring and different structure materials of the bracket were discussed by using modal analysis. The frame-type bracket can improve the first-order nature frequency of the gyroscope assembling through its spatial structure, and the mounting-interface dimension of fiber-ring had obvious effect than the wall thickness of the bracket on improving the first-order vibrational mode of the gyroscope assembling. By optimizing the wall thickness of the bracket and mounting-interface dimension of fiberring together, the first-order nature frequency of the gyroscope assembling increased 226 Hz. For the light weight design of triaxial integrated FOG, the magnesium-aluminum alloy did not have advantage in constructing of bracket of gyroscope to improve the mode shape of assembling, while the first-order nature frequency of the gyroscope assembling can increase 59% and the weight can decrease 74 g by using Be-Al alloy to build the bracket.