Many coloring substances existing in the fermented broth affected the application of cold-adapted protease MP in the product appearance. In this paper the decolorization of protease fermented broth by ion exchange resin was studied. The results showed that anion resin D352 could not only effectively decolor but also maintain relative high enzyme activity. The optimum pH was 6 ~ 7,the optimum temperature was 30℃,and the optimum flow rate was6 BV /mL. Anion resin D352 could absorb coloring substances as well as a large number of other proteins and the protein removal rate was 45. 2%. After 6-circle uses,anion resin D352 still had a good decoloring effects.