Abstract: Based on the classification and principle of pneumatic conveying system, the technical characteristics of reverse circulation fixed-point sampling device in underground coal mine are analyzed. It is pointed out that the reverse circulation sampling process belongs to pressure conveying. Use the method of pneumatic conveying engineering calculation, combined with the actual compressed air condition in the coal mine, it is obtained that a 73 mm wide blade auger with a 95 mm diameter drill bit has a center tube diameter range of 21 m to 32 mm; the experiment of simulation sampling system established in the laboratory shows that the 32 mm central pipe has better sampling effect in the same feeding quality and sampling time.