Abstract: The paper introduced structure and working principle of optical fiber gas sensor,and introduced working principle and new technologies of direct detection and tunable diode laser spectroscopy of multi-point fiber gas sensor system OptoSniff. The laboratory test results showed that the system has advantages of long transmission distance,fast response,high accuracy,and no periodic calibration. There is still a problem in application of the system in coal mine,namely the system can’t achieve in-place sound and light alarms.