NF-κB(Nuclear factor κB)as an ubiquitously expressed nuclear transcription factor, involves in regulating the expression of immune-related genes after activation by a variety of stimuli and thus plays a very important role in the innate immune system of fish. It reviewed the structure, function and the signal pathway of fish NF-κB. Furthermore, we reviewed the role of NF-κB signal pathway in the innate immune system in fish.