Gearbox rear cover airtightness test device

The utility model relates to a gearbox rear cover airtightness test device which comprises a first steel plate and a second steel plate, and the first steel plate and the second steel plate can clamp a gearbox shell. The air inlet valve can inflate the inner cavity of the gearbox shell; the number of the clamping hooks is multiple, hook tips of the clamping hooks are arranged close to the second steel plate, the clamping hooks are arranged on the first steel plate in a sliding mode, and each clamping hook is fixedly connected with an abutting block and a limiting block; the movable plug can move towards or away from the first steel plate, can push all the clamping hooks to move away from each other, and can drive all the clamping hooks to move towards the direction, away from the second steel plate, of the first steel plate; and the sealing plug can tightly abut against a mounting through groove body, adjacent to the side wall of the first steel plate, of the gearbox shell. The device has the advantages that