Self－demarcating, self－celebration and self－checking are the functions of the optical fibre temperature measuring system. The basic principle and structure of the optical fibre temperature measuring system and DOFTSS are introduced in detail. Methods of setting the benchmark value of the system, demarcating the system and realizing the baseline adjustment are also discussed. The structure of the system including parts of power supply, setting up and displaying and other controls is shown, as well as the system software flowchart. Prediction and warning system for fire hazard is set up making use of the technique of fiber temperature measuring system.