Gravel strata is a kind of typical instable layer in drilling engineering. By the analysis of present drilling ways, and according to the characteristics of gravel strata, application feasibility is put forward for DTH hammer concentric simultaneous casing drilling tool in gravel strata, and analysis are made on the structure principle and characteristic of drilling tool. With reference to the experiment results, the DTH hammer concentric simultaneous casing drilling tool is considered to have extensive application prospect in gravel stratum.