Abstract: In order to discuss the effect of soil fertility on composition transformation and energy change of corn stalk during decomposition, carborundum tube was used to study the decomposition of corn stalk buried in different soils with high, medium and low fertility for 480 days. The decomposition rate and change of energy states of corn stalk were revealed. The results showed that the fractions of alcohol-benzene soluble and water soluble decreased with the process of decomposition. The concentration of semicellulose and cellulose increased firstly and then decreased. However, the concentration of lignin increased. The change of energy states of corn stalk throughout the whole process could be divided into three stages such as fluctuating stage, decreasing stage and stable stage. Totally, the humification was a process of energy release. For 480 days of decomposition, the decomposition rate was highest in soil with medium fertility and lowest in soil with low fertility among three type of fertility. The decomposition of water soluble factions and lignin were promoted in medium fertility soil. However, alcohol-benzene soluble fraction, and semi-cellulose and cellulose fraction were decayed acceleratedly in soil with high fertility. Furthermore, more humic substance was formed and energy states of decayed corn stalk was highest in soil with high fertility.