Abstract: Two-stage and two-speed reaming technology was studied to solve the difficulty of pore-forming at high-position and large-diameter directional drilling in Wangpo Coal Mine. This paper analyzed several technical difficulties in construction. A specific two-stage and two-speed hole expansion technology based on the combination of mechanical energy with drilling fluid dynamic potential energy was developed. By matching triangular spiral drill pipes, actual drilling experimental research in coal mine showed that the mentioned technology can achieve once-through drilling for hole diameter from 120 mm to 200 mm, and average mechanical efficiency can be up to 20 m/h in complex sandstone roof. The technical proposed above reduces the workload of conventional hole enlargement construction greatly, avoids the occurrence of pressure holding and stuck drill caused by local hole wall collapse effectively.