Effects of external factors and five sterilizing processes on the stabilities of three anthocyanin extracts of black rice, black soybean and black corn were investigated by the colorimetry method. The results showed that the stabilities of three anthocyanin extracts from seed coats of black rice, black soybean and black corn were in a sequence of black soybean anthocyanin (BSA), black rice anthocyanin (BRA) and black corn anthocyanin (BCA) under the conditions of natural light, fluorescent light and without illumination. In the heating conditions, the BRA and BSA has a higher stability and the BCA has a lower stability. There were no significant effects on food materials such as NaCl, sucrose and glucose and preservative sodium benzoate and five metal ions of K+, Ca2+, Mg2+, Zn2+ and Cu2+ on the stabilities of these three anthocyanin extracts. The stabilities of these three anthocyanin extracts were significantly affected by five sterilizing processes of boiling sterilization, autoclave sterilization, pasteurization, microwave sterilization and high temperature short time sterilization, of which they were least affected by high temperature short time treatment, and most affected by autoclave sterilization.