Abstract: Abstract：In the process of directional drilling in coal mine, due to the drilling depth can be more than kilometers。Drilling formation also from pure coal gradually transferred to the complex strata. In the long depth drilling in complex formation, Common PDC bit was badly worn, and life and aging can not satisfy the using requirement. In order to solve this problem, a drag type PDC bit is developed in this paper. In the bit, drag type and shallow cone structure was used, more cutters can be arranged. The cutting angle and the side angle were chosen according to the formation. the bit was used in the n the directional drilling underground, and good effect has been achieved.

Key words: Keyword: Drag bit, Directional Drilling, PDC bit