Reliable sealing structure is the key to use the reverse circulation drilling technology for large-diameter reverse circulation DTH and is also the design point of large-diameter reverse circulation DTH. The sealing structure of existing large-diameter reverse circulation DTH is designed on basis of BHA body structure. A double sealing method at bottom and entrance of drilling hole is proposed in this paper, based on which as design principle, φ710/311mm cluster reverse circulation DTH and entrance sealing device were developed for reaming, the field test was made matching with φ127/70mm double-wall drilling tool, continuous reverse circulation effect was realized, the average ROP was 2.1m/h which was 2.6 times of the ROP of roller bit used in the same hole. The test results show that the double sealing method at bottom and entrance of drilling hole is feasible and it is worthy to be popularized.