Abstract: To prevent Penaeus vannamei turning red in the frozen process or in marketing,this study focused on factors that led to shrimp's reddening and explored the optimal countermeasures against reddening.Experiments were carried out to investigate factors such as p H,temperature,salinity and light intensity. The optimal countermeasures against reddening were determined by orthogonal experimental design.Inhibitor against shrimp 's reddening was selected by experiment of addition with small molecule amino acid. The results showed that p H,temperature and sunlight had a significant effect on P. vannamei reddening,but salinity 's influence was insignificant.Orthogonal experimental design revealed that reddening would slow down when the shrimp were frozen and kept from light. Moreover,with 1 ~ 1.5 mg / m L L- cysteine and the p H at 7.3 ~ 8.3,P. vannamei,in some way,could be free from reddening.