As its high construction efficiency in the bedrock, especially in the hard rock area, DTH drilling is the preferred technology. But in China, one-time reaming by DTH hammer with diameter of more than 660mm is not many, and one-time reaming and slag discharging by normal circulation cluster DTH hammer with diameter of 660mm is even fewer. The drilling test in Jinneng 2# gas drainage hole proves that reaming by use of 660mm cluster DTH hammer, one-time reaming and slag discharging with normal circulation can be realized, and there are also the advantages of rapid reaming, high drilling efficiency, short construction period and strong adaptability. The average drilling speed is 6.36m/h in hard rock formation and the highest is up to 9m/h, which is 10 times higher than normal circulation roller bit drilling. By this technology, the trapped personnel in mine disaster can be rescued in the shortest time, and drilling technical difficulties can be solved in water deficit area and serious loss zone.