Abstract: In order to improve the efficiency of directional drilling of hard rock in underground coal mine, based on the analysis of the orders of PDM for directional drilling in hard rock, the paper chooses four different types of PDM to make the directional drilling test in hard rock of underground Sangshuping coal mine in Hancheng. The test results show that one type of seven-eight-lobe PDM with four stages of power and another type of five-six-lobe PDM with five stages of power in directional drilling in hard rock, of which the average penetration rate is 2.52 meters per hour and 2.15 meters per hour respectively, and the cumulative drilling time can reach 550 hours. These two types of PDM show the characteristics of a long life and high efficiency and so on. They are suitable for directional drilling in hard rock.