The invention discloses an optical fibre fault locating device and an optical fibre fault locating method. The optical fibre fault locating device comprises an ASE light source, a filter, an optical fibre splitter, an optical fibre circulator and a data processing device; the ASE light source is used for generating ASE noise light; after being filtered by the filter, the ASE noise light is split into signal light and reference light by the optical fibre splitter; the reference light is output through the second output end of the optical fibre splitter, and acquired by the data processing device; after passing through the first output ends of the optical fibre splitter and the optical fibre circulator, the signal light enters an optical fibre link to be detected; reflected light at the fault position of the optical fibre link to be detected is output through the second output end of the optical fibre circulator, and acquired by the data processing device; the data processing device processes acquired signals; and thus, optical fibre fault locating is realized. By means of the optical fibre fault locating device provided by the invention, the problem that the locating error of an OTDR system is relatively large when long-distance detection is carried out can be solved; and high-precision locating of optical fibre faults can be realized.