The gas extraction in the determination of reasonable drilling hole sealing depth has been a problem in mine extraction, if hole sealing section in a loose zone, gas would be in the borehole drilled in the coal body around the periphery of the drilling hole sealing section of air leakage, serious influence drainage effect leaded to loss of labor, equipment and materials costs. Therefore, the reasonable drilling hole sealing depth was not only an important part of gas drainage, but also the key to improve the efficiency of gas drainage. Through the determination of gas emission initial speed q, S drilling cuttings volume per meter S, drilling time s three indicators determined reasonable hole depth, sealing can not only ensure maximum extraction occurrence in the coal gas, but also helpful to grasp the consumption situation of hole sealing material.