Abstract: Based on the importance of coal mine gas pipeline conveying safety, the article designs a fire barriering & explosion venting device of water seal with automatic water supply and drainage function; the device has backfire prevention, explosion venting and manual/automatic water supplement function, its strength design meets the nominal pressure ≥ 1 MPa, water seal height of 50 mm, explosion venting pressure of 0.09 MPa. The device does not need regular personnel observation and replenishment, and makes up personnel water supply shortage.