Abstract: The power head of coalmine tunnel directional drilling rig is the key part of directional drilling rig, and the performance of power head directly affects the whole drilling rig. The plan formulation and technical parameters were introduced in this paper including brake device, chuck, spindle, housing and gear design process. In the directional drilling industrial test, the accumulative total of trouble-free drilling of power head is more than 19 308 m, which meets the requirement of coalmine tunnel drilling rig.