A type of fiber ring laser gyroscope based on a polarization splitting filter is presented, and its principle of bidirectional operation and the generation of beat frequency is analyzed. The mode energy coupling can be adjusted by controlling the filter. When the pump power exceeds 10 mW, bidirectional single-mode oscillations can be achieved, and the beat frequency can be switched from 50 kHz to 1.5 MHz by filter control. Finally, a linear frequency-rotation response curve of the gyroscope with the initial beat frequency set at 70 kHz is obtained.