In recent years,the health monitoring of large bridges,buildings and transmission towers has become a research hotspot.Brillouin optical time-domain reflection(BOTDR)fiber sensing is widely used because of its advantages of distributed temperature/strain simultaneous sensing,single-ended injection and measurement.In this paper,we review the mechanism of BOTDR sensing for long-range fiber sensing applications;the development and key technologies and specific indicator values of 10 km and above long-distance BOTDR fiber sensing system in recent 20 years;we summaries the principle of long-range BOTDR optical fiber sensing system based on technologies of data processing,pulse coding,multi-wavelength detection,high extinction ratio modulation,Raman,narrow linewidth light source and single-photon detection.Further improve the system signal-to-noise ratio,spatial resolution,sensing distance,shorten the measurement time of the whole system,optimize multiple performance parameters;and further increase the sensing parameters excepting temperature/strain,enhance the system function;as well as further addressing temperature/strain cross-sensitivity issues;all will become the future development direction of long-distance BOTDR optical fiber sensing system.