Abstract: Based on the theory research of gas detection, using the zero self adjustment theory to underground gas detectioin, this paper is mainly about the designing and exploiting of a brand new gas detection instrument with zero self adjustment. The main point in zero self adjustment is to reduce the sensor’s working current right under its working point by MUX switching after each certain period of time in order to stop its working procedure for a short time. In this way, we can simulate the normal zero adjustment in air by taking down the data of “zero” at this time and compensate the following data with this “zero”. The theory and the experiments of zero self adjustment used in this paper show the complete feasibility and the stable work performance.