Abstract: A directional measurement system for auger pipe with an outer diameter of 63.5 mm is developed. The measuring tube of the system is connect with the explosion-proof computer through the drill pipe with central cable, and the underground AC 127 V is used to the power supply for measuring tube and explosion-proof computer, and the measured data are transmitted by digital carrier signal through the cable drill pipe to the explosion-proof computer at the orifice in real time, which can display, store and draw the data in real time. Performance tests shows that the system can meet the requirements of directional drilling in the construction of small drainage hole or small gas drainage hole in the coal mine.