The sensors based on fiber laser cavity have been widely used in the detection of temperature, strain, sound wave, vibration, magnetic field, voltage and other physical quantities, and compared with traditional optical sensors, fiber laser sensors have the advantages of anti-electromagnetic interference, narrow line width and high signal-to-noise ratio, so they have broad application prospects. This paper reviews the research progress of sensing applications in fiber laser cavities. Ring cavity and linear cavity are described, and the working principles of fiber laser sensors based on different cavity structures are summarized; in addition, according to the classification of temperature, solution, magnetic field and stress/strain, the performance of fiber laser sensors are introduced, and the future application prospect is prospected.