This article provided a techniche of using Fiber Bragg Grating(FBG) sensors to mornitor natural gas pipeline leak in real time,which sovled the promblem that traditional methods can't diagnose the gas pipeline leak in high precision.It discussed FBG system and distributed optical fiber leak detection system based on their temperature features and the temperature change rules of natural gas pipeline leak.It analysed the principle and structure of FBG system and distributed optical fiber leak detection system,and introduced the advantages of the systems.finally,a project using this techniche was showed.