This paper mainly introduces the basic working principle， technical performance and application of hydraulic pipe cutter for small diameter drilling in geological core drilling in southern Shanxi and Beishan areas. The practice shows that compared with other types of pipe cutters， the hydraulic pipe cutter has the advantages of simple design， convenient operation and high working efficiency. It has played a huge role in the treatment of drilling stuck， buried drilling and other accidents， and has achieved good application results. At the same time， there are also some problems in the practical application of hydraulic pipe cutter， such as the welding quality of the tool head is not high， the existence of ring cutting vibration and the phenomenon of the tool head falling edge. Through the analysis and summary of the actual application， some suggestions are put forward to improve the existing problems， so as to promote the application of the equipment.