Abstract: The effect of a long-term organic manure application on different available carbons in red soils are discussed. The results indicate that comparing the organic manure treatment with CK, different available carbons have different improvements on red soil. Effects of different treatments on the C_MB and C_T, C_M are green manure＞farmyard manure＞rice straw＞straw returned to farm＞CK and farmyard manure＞green manure＞rice straw＞straw returned to farm＞CK respectively. Effects of different treatments on the C_A, A_AC, A_BC, A_CC and CPMI are green manure＞rice straw＞farmyard manure＞straw returned to farm＞CK. Green manure and rice straw have a better improvement on soil physical and chemical feature and fertility. CPMI is well related to soil nutrient factors and is sensitive to agricultural measures, which indicates that it is practical to assess soil C pools under different management practices using CPMI.