Blast testing device for detecting air tightness in building

The utility model discloses an air blast testing device for building interior air tightness detection, which comprises sealing cloth and a combined type inner supporting door frame, a strip-shaped air bag is wound on the periphery of the combined type inner supporting door frame, and the outer ring of the strip-shaped air bag flexibly supports and blocks the sealing cloth of a building door frame in the building door frame; the width and the height of the combined type inner supporting door frame are adjusted in a matched mode according to the size of a building door frame, and a plurality of air blowers are rotationally supported in the middle of the combined type inner supporting door frame. A plurality of openings for accommodating air blowers are formed in the middle of the sealing cloth. The air blast testing device can perform flexible radial air pressure sealing between the sealing cloth and concrete in a building door frame, performs synchronous positive pressure or negative pressure testing of a plur