In recent years， with the national emphasis on mine safety， vocational health， environmental protection and other aspects， large diameter boreholes have been widely used for gas drainage， water cut-off grouting， supply of nitrogen gas for extinguishing， supply of ice for cooling， drainage and ventilation， emergency rescue， etc. in mines. The large diameter boreholes range from ?500 mm to 1500 mm in diameter with depth less than 1000m. Proper selection and design of the borehole structure and the drilling method can minimize construction cost， and improve drilling efficiency and drilling safety.