Abstract: Bursin is an active factor in bursa of fabricus and it’s composition has been known to us. Bursin plays an important role in immunoloregulation.Up to now,we have made great progress in research the bursin. In order to research and apply the bursin much better, this paper will reviewe the chemistry essence，tissular location，biological activity，preparative method，content determination，molecular biology research and immune mechanism of bursin. Moreover，this paper identified the problems that need to be further researched and its wide application future.

Key words: bursa of fabricius; bursin; tripeptide