Water gushing after the closure of Wangtaipu Mine has threaten the safety production of adjacent mines. Water drainage with large-diameter straight drainage wells is an important approach to reduce the above impact. According to the coal seam geology and water inflow， the diameter of the straight drainage well is designed as ?650 mm. Since the target stratum is a roadway and passes through the goaf of No.3 coal seam， the conventional drilling method will somehow compromise the safety of the target stratum， and it also has slow drilling speed with high cost. To this end， this paper proposes a new casing drilling technology with the large-diameter DTH hammer， where the rock is broken by the DTH hammer， and the casing is used to reduce the up-hole annulus area， hence the the air consumption， eliminating effectively the technical problems of large air volume demand and high cost in large-diameter air drilling. This paper expounds the working principle， characteristics and equipment composition of the technology， and analyzes its application results in the construction of three large diameter straight drainage wells in Wangtaipu Mine. Field application shows that this technology has low air consumption， good cleaning of cuttings and excellent sealing performance. The average well construction period of the 3 large diameter straight drainage wells is 20 days with the average drilling efficiency of 10m/h. It greatly improves the large diameter drilling efficiency， reduces the drilling cost and provides important reference for large diameter drilling.