Abstract: Co-pigment method was used for enhancing the stability of red pigment from purple sweet potato (PSPP) . Preliminary experiment was carried on selecting three co-pigments with better effects, and orthogonal test design was adopted to determine the best combination and adding contents, also the stability of the pigment on heat, light and food additives after adding co-pigments was studied. The results indicated that:three co-pigments with better effects were orderly listed as L-cysteine hydrochloride, tannin, citric acid. The optimum co-pigments parameters were as follows:L-cysteine hydrochloride 0.6g/L, tannin 0.2g/L, citric acid 3g/L. Using the optimum co-pigments parameters, the resistance of the pigment to heat and light was obviously improved. Co-pigment effects of Fe3+ and Al3+ were enhanced, and bad effects of Fe2+ and Cu2+ were reduced. The resistance to benzoate sodium, H2O2, Na2SO3 were all increased slightly. The stability of PSPP was largely improved and enhanced after adding co-pigments, and its application value was greatly improved.