The new generation of optical fiber sensing system based on fiber ring laser (FRL) cavity detects the changes of external parameters by demodulating the laser wavelength shift, which benefits from the characteristics of narrow line-width and high signal-to-noise ratio of the laser, and can realize high-resolution and large-scale dynamic monitoring. This paper introduced the basic working principle of fiber ring laser cavity sensing technology, and summarized the most mature fiber microstructure sensors in recent years, including fiber grating, Michelson interferometer (MI), Fabry Perot (FP) cavity, Sagnac loop and Mach Zehnder interferometer (MZI). The principle of each structure and the specific application scenarios in the field of optical fiber sensing were described. Finally, the development and application of optical fiber sensing technology based on fiber ring laser cavity were summarized and prospected.