In the high-temperature geothermal drilling construction in the Tianyang Basin, affected by the lithology and high temperature of the hard rock strata of the metamorphic rock system, the cone bit has low mechanical drilling efficiency, serious wear and tear, and short service life , which seriously affects the drilling construction.The application of PDC drill bit was explored.Aimed at the formation lithology characteristics, the key technologies such as the selection and layout of bit body, blade, profile and composite pieces were explored, and optimized and improved in drilling practice, a PDC drill bit with good impact resistance and suitable for metamorphic hard rock formation is developed.It effectively improves the mechanical drilling speed and reduces the drilling cost, provides technical support for the smooth implementation of the high-temperature geothermal drilling project in the Tianyang Basin.