Abstract: Owing to the inherent characteristies, such as high sensitivity, continuous measurement, the radioisotope tracer technique becomes one of good research methods used in various fields, and has got a great progress in recent years@In this paper some successful applications are introduced, including study of distribution of elements in steel metals or alleys, detection of rare-earth elements in molten iron and its reaction on refractories, monitoring of contamination, detection of leaks and mechanical wear.@The tracer technique has been proved to be an effective and beneficial methed under a variety of conditions and will play an important role in research works.