Based on the analysis on the requirements of PDC bit structure, 3 different types of PDC bit were selected for hard rocks directional drilling tests in underground coal mine in order to improve the drilling efficiency. The test results show that the flat-bottom PDC bit is not suitable for directional drilling in hard rock, the three-wing parabolic PDC bit and the four-wing straight angle PDC bit show the adaptability in hard rock directional drilling with long service life and high efficiency.