Abstract: Melanosis in shrimp reduces the customers' acceptability drastically, leading to the decreasing of market values and considerable financial loss, which is triggered by a kind of enzymes called phenoloxidase.Phenoloxidase oxidizes tyrosine to quinine leading to black high molecular weight pigment.Studies on the mechanisms of phenoloxidase activation system and phenoloxidase inhibitory methods domestically and abroad were reviewed, in order to provide information for further study and development in shrimp preservation techniques.