Coal and gas outburst mines need to be pre-drilled to eliminate the dangerous work. In the process of drilling, the blank belt often appears due to the deviation of the borehole. In order to explore the distribution of the blank belt in the pre-drilling hole, the drilling trajectory measuring instrument was used to measure the hole trajectory of the pre-drilling hole. The Drilling trajectory measuring device can realize the three-dimensional drilling view to determine the deviation of the drilling hole in different directions. It was found through experiments the actual hole-forming trajectory of the borehole was larger than that of the horizontal direction of the design trajectory. The main factors causing the large displacement of the borehole in the horizontal direction were the influence of the self-weight, geological conditions and drilling process of the drill pipe. According to the distribution of the blanking zone of the drilling hole, the hole was filled, the accuracy of the tunneling face was improved, and the safe production of the mine was ensured.