Abstract: To understand the stability of phycocyanin and broaden its application in food, in this paper, the stability of phycocyanin under different pH, temperature and light intensity, and the influences of common additives on the stability were studied by ultraviolet-visible spectrum scanning and color difference analysis. The results showed that phycocyanin had the smallest color loss and the highest storage rate without precipitation when stored at pH 4.0-7.0, temperature below 55 ℃ and protected from light. When the mass fraction of sucrose, glucose and fructose were 4%, 6% and 6%, respectively, phycocyanin had the highest preservation rate at room temperature. Sodium chloride, potassium chloride, ammonium sulfate, calcium chloride, magnesium sulfate and copper sulfate solutions all caused the precipitation in the phycocyanin solution, and the color became lighter. Although no precipitation was caused by sodium sulfate, the color of phycocyanin was completely lost. Different concentrations of ascorbic acid and citric acid had a great destructive effect on the preservation of phycocyanin. SDS (0.06% mass fraction) showed the best effect on reducing the color loss of phycocyanin without precipitation at pH 2.5. The five polyphenols had insignificant improvement effect on the color loss of phycocyanin at pH 2.5. Therefore, the phycocyanin should be stored under the conditions of neutral pH, low temperature, darkness, metal ions and antioxidants. The stability of phycocyanin can be improved by adding certain amount of SDS or sugar.