The pneumatic DTH hammer drilling technology has been used in ground source heat pump exploration well drilling in complicated geological conditions in the karst area of southeast Guizhou with accumulative drilling amount of 568m, which has not only found out the geological conditions and drillability of the proposed project area, but also successfully implemented a test well through the change of the drilling process to ensure the smooth development of the project. This paper analyzes the problems encountered in drilling in karst areas. With change of the drilling technique to indirect sim-casing drilling with the pneumatic DTH drilling hammer, the continuity of drilling has been ensured, and the experience gained can be used for reference.