To reduce the power consumption, volume and the weight of a fiber optic gyroscope, the structure of a time division multiplexing fiber-optic gyroscopic system worked at 850 nm was presented based on a 3×3 coupler. The data processing method of gyroscopic output was analyzed, and the relative bias stability of the time division multiplexing system was obtained. A switching model of the time division multiplexing fiber-optic gyroscope was established, which pointed out that there is a transient process in axis switching. The effects of the transient process on the static and dynamic characteristics of the gyroscopic system were analyzed, which shows that the relative bias stability is about 2.1 times that of the traditional method, the maximum bandwidth is about 1.1 kHz and both the nonlinearity and uniformity of the real scale factor are less than 50×10-6. Finally, the results were tested and verified by simulations and experiments, and results indicate that the time division multiplexing can satisfy the requirements of applications to micro-miniature fiber-optic gyroscopes.