In this study, two different kinds of commercial enteral formulas were selected to evaluate the changes of vitamin A, E, C and thiamine during the different storage conditions of different temperature and relative humidity (60 ± 1 °C, 60 ± 5% for 5 and 10 days; 37 ± 1 °C, 75 ± 5% for 1, 2, 3, 5 and 6 months; 25 ± 1 °C, 60 ± 5% for 3, 6, 9, 12, 18 and 24 months). The results showed that as the temperature or time increased, the content of vitamin A, E and thiamine was gradually decreased whilst the level of vitamin C remained stable. The vitamins exhibited more stability at the storage of 25 ± 1 °C, RH 60 ± 5%. Vitamin A and thiamine decreased more in the polymeric formula (EFA) than that in the oligomeric formula (EFB), while, vitamin E decreased less in EFA than that in EFB. The kinetics of vitamin A, E and thiamine degradation during storage followed first order kinetic equations. Furthermore, the final levels of vitamins were higher than the minimum level recommended by legislation.