Optical frequency domain reflectometer (OFDR) is a distributed optical fiber measurement technology. The scanning laser is injected into the optical fiber link, and the position and intensity of the reflection points on the optical fiber link are located by analyzing the Rayleigh backscattering scattering light in the frequency domain. Because of its high precision, high spatial resolution and other characteristics, it is widely used in aerospace, intelligent structure, material processing, optical network monitoring, biomedicine and other high precision measurement and manufacturing fields. In this paper, the basic principle of OFDR is described. The research progress of key technologies to improve OFDR performance is introduced. Finally, the application of OFDR in different fields and to the future development trend are summarized and prospected.