Abstract: The faults have great influence on coal and gas outburst disasters, and accurate detection of faults location is very important to prevent such disasters. At present, large number of gas drainage boreholes were drilled in coal mines, but the geological information contained in these boreholes is not fully paid attention to, thus the method to detect concealed faults by gas-drainage boreholes was proposed. In this paper, by establishing a mathematical model for fault detection based on gas drainage drilling, a three-dimensional coordinate of fault planes and coal seam floors is calculated, and basic parameters such as fault location, drop, attitude and fault properties are determined by drawing contour maps of coal seam floors and their three-dimensional maps. Based on the graphical user interface(GUI) of Matlab, a software for fault detection by gas drainage drilling is designed to visualize fault information and provide a technical platform for accurate fault identification. The technical method of detecting small hidden faults by gas drainage drilling is successfully implemented through a combination of drilling location, model calculation, image processing and fault identification.