Abstract: Whether does the drill hole seal key lie in the material effective backfill drill hole peripheral crevasse, and the sealing length is long enough.Through the combination of Portland cement, sulphoaluminate cement clinker, lime, gypsum and other materials can get an active expansion, high strength of the sealing material.The material sealing experiment in Zheng'gao coal mine, and the original method only using Marithan bag sealing , The gas drainage concentration have increased significantly.