Abstract: A stratified sampling method was used to study the oxidation stability and the chemical forms of soil organic carbon (SOC) for two-year old alfalfa, for Bromus inermis, and for a mixture of the two. SOC of the alfalfa only was the highest at 0-40 cm, followed by the interlaced mixture. There was a highly significant difference (P＜0.01) compared with the single B. inermis and with the mixture components in the same line. Coefficient of SOC oxidation stability of the interlaced mixture (1.27) was greater than that of the mixture in the same line (1.16). There was a highly significant difference (P<0.01) compared with the single alfalfa (0.99) and the single B. inermis (0.94). It showed that the mixture was beneficial to the oxidation stability of SOC. The chemical bondings of SOC were mainly in the forms of Fe (Al)-bound and under different treatments and at different layers, the content of Fe (Al )-bound SOC was higher than that of Ca-bound SOC (P<0.01).