A frequency based ring laser sensor is disclosed. The sensor includes a pump source, a common section, and a reference section and a detection section. The common section is provided with a gain medium. The common section and the reference section form a first ring laser resonator, and the common section and the detection section form a second ring laser resonator. Laser beams are transmitted oppositely in the first ring laser resonator and the second ring laser resonator. The detection section is provided with a sensing element capable of causing an optical path difference. The common section is provided with an output unit or each of the reference section and the detection is provided with the output unit, and the output unit is connected to a photoelectric detector through a light uniting unit.