Abstract: To clarify the application status of existing fault location technologies for optical fiber loops in smart substations, this paper reviews the research progress of fault location technologies for optical fiber loops in smart substations. Firstly, this paper expounds the causes and characteristics of physical damage faults, environmental impact faults and material quality faults, sorts out three types of optical fiber fault location methods based on physical modeling, data-driven and hybrid-driven approaches, and summarizes the application status of optical fiber fault location systems in smart substations. Secondly, this paper identifies three core challenges of existing technologies: ambiguous fault mechanisms of multimode fibers, poor multi-scenario adaptability of location methods, and insufficient system compatibility, stability and intelligence. Finally, this paper prospects that the application bottleneck of fault location technologies for optical fiber loops in smart substations can be broken through in the future by decoupling the complex fault mechanisms of multimode fibers in multi-physical fields, applying physical-data hybrid-driven fault location methods, and constructing standardized, collaborative and intelligent fault location systems.