Based on molecular structure and physical and chemical properties, we compare the characteristics of melanin separation and purification by different methods, and summarizes the antioxidation, immunomodulation, radiation protection, antiviral, chelated metal ions, antitumor, organ protection, anti-inflammatory and antibacterial properties of melanin. Biological activities, such as DNA protection, focus on the characteristics and mechanisms of antioxidant, metal chelation, anti-tumor, and radiation protection, and provide guidance for the higher value utilization of melanin.