An isentropic light piston tunnel, a form of intermittent tunnels, is useful for studying the instantaneous heattransfer. In the paper the theories, the characters and the advantages of this kind of tunnels are explicated and the comparisons with other intermittent tunnels such as shock tunnel, gun tunnel and Ludwieg tube are carried out. As a result, the basis for choosing the right type of tunnel according to different conditions is provided.