Clamping device

The utility model discloses a clamping device. The clamping device comprises an air cylinder and a first mounting unit. The inflator is mounted on the first mounting unit, and an elastic structure is arranged between the inflator and the first mounting unit; a self-locking operation structure is arranged on the first mounting unit and can drive the inflator to reach and be locked at the connecting position. According to the gas meter calibration device, the gas cylinder guides gas into the gas meter to calibrate the gas meter; the gas meter to be tested is arranged at the bottom of the gas cylinder, the self-locking operation structure is rotated, the gas cylinder continuously descends under the driving effect, and when the self-locking operation structure is rotated to a self-locking state, the gas cylinder descends and is maintained at the connection position, and connection with the gas meter is kept; when gas meter verification is completed, the self-locking operation structure is reversely rotated, the s