Abstract: The accurate detection of tracer gas is the key to the monitoring and early warning of coal mine internal fire, there is no precise quantitative tracer gas detection equipment with the level of 1×10^-9, the accuracy improvement of detection equipment is an effective way to enhance the effectiveness of coal mine internal fire warning. The cavity enhanced absorption spectroscopy detection technology is studied, it is obtained that the precise online detection method for coal mine sulfur hexafluoride tracer gas, which provides new ideas and new methods for causal factors analysis and early warning of coal mine internal fire.