Coal seam gas pressure measuring system and method

The invention discloses a coal seam gas pressure measuring system and method. The coal seam gas pressure measuring system comprises a constant-pressure automatic supply unit and a pipeline pressure measuring unit. The constant-pressure automatic supply unit is connected with the pipeline pressure measuring unit; the coal seam gas pressure measuring method comprises the following steps: S1, feeding a pipeline pressure measuring unit into a pressure measuring drill hole; s2, a grouting pump is used for pumping cement paste into the grouting pipe, and the cement paste enters the bags and the area between the two bags; s3, mucus is fed into the area between the two bag hole sealing assemblies through a manual liquid pump; s4, the high-pressure air source bottle is opened, mucus in the mucus tank enters the mucus pipe, and constant supply of mucus in the mucus pipe is achieved; s5, after pump injection of the mucus tank is finished, gas pressure observation is conducted through a first pressure gauge on the pressu