Abstract: The effects of light, temperature, pH value and metal ions on stabilities of L-ascorbyl decanoate,L-ascorbyl laurate and L-ascorbyl palmitate in ethanol were measured by iodimetry. Results showed that light,high temperature and alkaline conditions could affect their stability. They were stable in acidic and neutral conditions and when metal ions such as Mg2+,Ca2+,Na+and Fe2+were added. It also showed little differences of stabilities among L-ascorbyl decanoate,L-ascorbyl laurate and L-ascorbyl palmitate in the same conditions except in illumination conditions.