According to the actual demand of high-level large-diameter directional drilling rig for underground roof in coal mine, a complete set of directional drilling rig equipment with a primary hole diameter of more than 153 mm is developed. The key technologies such as the overall layout of the drilling rig, large-flow mud pump truck, large-torque power head, large thrust feeding system, “brake priority” logic control hydraulic system, auxiliary rod loading device and other technologies are studied. The results of rig performance test and industrial test in Hebi No.3 mine, Henan Province show that the overall performance of drilling rig is stable, and the sludge discharge capacity of mud pump truck is strong, which greatly improves the diameter and depth of hole forming at the top level of the roof.