Abstract: The corrosion inspection on heat transfer tubes of steam generator is an important problem which ensures the security of the nuclear plants. Based on the principle of acoustic emission （AE） technique, acoustic emission signals about tubes of steam generator gathered by instrument were analyzed. The results show that corrosion dots come into being for tubes of steam generator, and the corrosion dots develop deeply to form tip corrosion which extends to become crack gradually, which causes serious leaking accident. The realtime inspection on the work of steam generator was achieved, according to which the stress corrosion can be judged timely. So the operator can control the nuclear plants according to intensity of acoustic emission signals.