Abstract: For problems of obturation of drilling hole's sealing section, collapse of soft hole-wall of multi-seam and pressure distinguishing caused by hole-wall fissure connecting of multi-seam in detecting gas pressure by puncturing multi-seam, the paper proposed a technology of detecting gas pressure by puncturing multi-seam based on M-Ⅱgas pressure detector and casing method. It expounded principle and technique of the technology and introduced concrete application of the technology in detecting gas pressure in some coal mine. The test result by indirect calculation method of gas pressure in coal seam showed that the technology can detect original gas pressure in coal seam accurately and quickly with good effect.