Abstract: High mobility group protein B（HMGB） is a kind of non-histone protein bound to chromatin that ubiquitously exists in the nucleus. Currently, it has been found that fish HMGB family contains three subtypes, HMGB1, HMGB2 and HMGB3. As cytokines, HMGBs mediate infection, injury, and inflammation by regulating DNA replication, transcription, recombination, and repair. Thereby, HMGBs play an important role in the resistance of fish to pathogenic microorganisms such as bacteria and viruses. In order to provide new ideas and theoretical reference for the application of fish HMGBs in production practice, the structural characteristics and immunological functions of fish HMGB family members were reviewed in this paper.