Abstract: Studies have been carried out on the characteristics of bubble detectors for registration of high energy heavy ions using large sizes of bubble detectors made in China Institute of Atomic Energy. The studies show that:(1) Bubble detector is a new type of threshold detectors for heavy ion registration. The essence of the threshold can be expressed by critical energy loss rate. (2) The maximum track lengths of the heavy ions are corresponding to their atomic numbers one by one, by which the atomic numbers of the heavy ions can be identified. (3) A relationship between linear bubble density and energy loss rate d E /d X can be recognized in a certain interval of the track. The atomic number and energy of the heavy ion can be deduced from the distance between two points in the interval and linear bubble densities at the two points of the track. Bubble detector has the capability to identify heavy ions and is immediate, realtime and visible detector without requirement of additional instruments.