The invention discloses a multichannel distribution type optical fiber temperature sensing system. The system is characterized in that: a processing and control system is connected with at least one photoelectric module through a bus interface; the photoelectric modules are connected with a pulsed light source and 1*n couplers respectively; and in the multichannel scheme, the flexible multichannel expansion can be realized on the premise of not reducing the total detection time of the system, the channel of the system can be expanded according to requirements, and the detection time of the system is not considered; and compared with the prior art, the system has the obvious substantial characteristics and progress.