Distributed sensing is widely used in various sensing fields because of its characteristics of large capacity, high spatial resolution, and long sensing distance. However, with the growing demand for high-precision sensing, it is difficult for the traditional optical time domain reflectometer to meet the demand for spatial resolution. Therefore, the optical frequency domain reflectometer with higher spatial resolution potential has attracted more and more attention, and gradually showed its advantages in multiplexing optical components. This paper reviews the research progress of optical frequency domain reflectometer, including the development of high spatial resolution and long limit sensing distance, introduces the current distributed sensing applications based on optical frequency domain reflectometer, and summarizes the composite sensing technology of optical frequency domain reflectometer, including the composite sensing technology combined with fiber grating, Fabry-Perot interferometer, and cone fiber. Finally, the prospect of optical frequency domain reflectometer technology is given.