The invention discloses a long-distance optical fiber Brillouin optical time-domain analyzer which comprises sensing optical fiber, main equipment mainly comprising a detection light source, a frequency measurement, a signal output module, a main equipment controller and a first remote communication module, and slave equipment comprising mainly comprising a pumping light source, a polarization scrambler, a slave equipment controller and a second remote communication module; the main equipment and the slave equipment are positioned at the two ends of the sensing optical fiber; frequency measurement of continuous light output by the detection light source and the pumping light source as well as receiving of backscattering signal of the sensing optical fiber can be realized through the frequency measurement and the signal output module of the main equipment; and the slave equipment is controlled through the communication and interaction of the first remote communication module and the second remote communication module. The long-distance optical fiber Brillouin optical time-domain analyzer has the advantages that under the premise of not sacrificing spatial resolution, measuring accuracy and measuring time, the measuring distance can be effectively increased by one time, the maximal measuring distance can reach more than 120 kilometers, and the application range of the optical fiber Brillouin optical time-domain analyzer is effectively enlarged.