Abstract: In order to separate and purify the bioactive peptide, the color material of soy sauce should be removed. Based on decoloring rate and loss of soy sauce peptide detected, the adsorptive decolorization technology of the soy sauce peptide solution was investigated. The decoloring time was 40min which was determined by the single -factor experiments, then optimal conditions were carried out by response surface methodology. Optimal technical conditions were as follows:1.8% activated carbon (w/v, %) , temperature 54.9℃ and decoloration pH of 6.4. Under the optimal conditions, the decoloring rate was 80.94% ±0.45% , in further verified experiment and the difference was not significant with predicted value of 81.09% . The method was effective, simple and reliable. Active peptides obtained by this method could be used to further separation and purification, sequence analysis, and biological activity. This study provided theoretical foundation for the development of functional factor-rich soy sauce.