The present invention provides an air tightness detection device for an aluminum alloy wheel hub, which is characterized by precision air pressure sensors, a lower clamp, a cone cylinder pressure plate, air pipes, a pressure plate, guide posts, an air inlet pipe, and a compressed gas control and detection system. A technical solution of the present invention has the following advantages that the cone cylinder pressure plate of the detection device reduces the space of an inner cavity of the wheel hub to further reduce inflating volume, thereby increasing detection efficiency; the characteristics of readily availability for preparation, no pollution and low cost are achieved by taking compressed air as a leakage indication gas.