The present invention discloses a rotary wheel airtightness detecting machine which comprises a body frame, an air cylinder, an upper seal, a lower seal, a water tank, an electric motor and a self-made air cylinder, etc. During use, the present invention can make the wheel be automatically centered between the upper seal and the lower seal, avoiding severe abrasion of equipment caused by inclination of the upper pressing plate for sealing upon biased positioning of the wheel.