Air tightness detection device and air tightness detection method

The invention discloses an air tightness detection device and an air tightness detection method. The air tightness detection device comprises a detection assembly, the detection assembly is provided with a liquid cavity, one end of the liquid cavity is provided with an insertion port, and a bottle valve of a fire extinguisher can be hermetically inserted into the liquid cavity through the insertion port; the detection assembly is further provided with a thick inner cavity and a thin inner cavity, the thick inner cavity and the liquid cavity are arranged in a spaced mode through an elastic membrane, the thin inner cavity is vertically arranged and communicates with the top of the thick inner cavity, conductive liquid is stored in the thick inner cavity, a resistance wire is arranged on the inner wall of the thin inner cavity in the vertical direction in an exposed mode, and the two ends of the resistance wire are electrically connected with a resistance value detection module. And the elastic membrane can defo