Medium and deep geothermal energy is a kind of renewable energy which is abundant， widespread， stabable and reliable. It is characterized of green and low-carbon， clean and environmental protection， safe and high quality， sustainable and stable energy supply， which plays an important role in the implementation path of carbon peak and carbon neutrality. Combined with an engineering case in Changsha Basin， this paper tests the hardness， uniaxial compressive strength and lithology of rock samples using the rock pression sclerometer， electric-stress direct shear instrument and polarizing microscope.The influence of rock cementing material， mineral particles and bedding development degree on the drillability of the strata is analyzed and studied. The drillability grade of the strata is established， and some suggestions on the drill bit optimization are put forward， which has certain reference significance for drilling engineering in this area and such similar areas.