A full-fiber Mach-Zehnder interferential measurement system for local range temperature shift is designed.The basic instructure and theory of the interferometer are introduced briefly

and the relation between shift distance of interferential fringe and length change of measurement branch is deduced.On the basis of theroretic analysis

a full-fiber Mach-Zehnder interferometer system is set up

the temperature change of measurement branch is determined through the directly observing interferential fringe shift distance on the scaled receiving screen

and the relation of interferential fringe shift distance and measurement branch heating temperature is achieved finally.The conclusion is drawn from the analysis of experiment results that the interferential system can measure exactly the local range temperature shift and the measure precision is ℃/18.