Abstract: According to the problems that borehole collapse and low efficiency of gas drainage in soft coal seam, a wall protection process of new screen pipe was developed. It used the inner diameter of drilling pipe to put screen pipe to the borehole bottom before drilling backward, it could make sure smooth flow of gas drainage channel, and improve the efficiency of gas drainage. In order to satisfy the process, the large hole open-closed bit, the path drill pipe and the fixing device of screen pipe were developed. By the experiment in Xinji No.1 Coal Mine, the lower rate of screen pipe could achieve 99%, which realized the target that drilling in place, the pipe in the bottom, so the gas extraction concentration was improved effectively.