Quantification of soil organic carbon as affected by forest succession can facilitate conservation and restoration of the secondary growth forests and increase understanding of the potential for forest ecosystems to sequester carbon. The active pools of soil organic active carbon and its correlations with soil nutrients were investigated for four forest types in central Hunan, China. The four forest types included Cunninghamia lanceolata plantation(PM), Pinus massoniana+ Lithocarpus glaber mixed forests(CL), Choerospondias axillaries deciduous broad leaved forests(CA) and Cyclobalanopsis glauca +Lithocarpus glaber evergreen broad-leaved forests(CG), and the last three forests represent the natural secondary growth forests at different successional stages in the subtropical region.. The results showed that (1) The contents of total organic carbon (TOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC) and easily oxidized organic carbon (EOC) in the same soil layers were in the following order: Cyclobalanopsis glauca and Lithocarpus glaber evergreen broad-leaved forests > Choerospondias axillaries deciduous broad leaved forests > Pinus massoniana+ Lithocarpus glaber mixed forests > Chinese fir plantations at the 0-30cm soil layer. Specifically, the content of TOC was 13.40%, 19.40% and 29.91% higher in Pinus massoniana+ Lithocarpus glaber mixed forests, Choerospondias axillaries deciduous broad leaved forests, Cyclobalanopsis glauca and Lithocarpus glaber evergreen broad-leaved forests than in the Chinese fir plantations, respectively. The corresponding values were 15.62%, 32.89% and 53.33%, 8.52%, 8.75% and 13.76%, and 32.79%, 38.48% and 78.30% for the contents of MBC, DOC and EOC, respectively. (2) In the different soil layers under natural secondary growth forests, the ratio of MBC to TOC displayed the following order: Choerospondias axillaries deciduous broad leaved forests > Cyclobalanopsis glauca and Lithocarpus glaber evergreen broad-leaved forests > Pinus massoniana+ Lithocarpus glaber mixed forests, and all of the values were higher than that in the Chinese fir plantations at the same soil layer, except the ratio of Pinus massoniana+ Lithocarpus glaber mixed forests at the 15-30cm soil layer. The ratio of DOC to TOC decreased with the advanced stages in the succession series, and the values were lower in the secondary growth forests than in the Chinese fir plantations, except the ratio of Pinus massoniana+ Lithocarpus glaber mixed forests at the 0-15cm soil layer. The ratio of EOC to TOC increased with the progress of the successions, and the values were higher in the different successional staged forests than in the Chinese fir plantations. (3) MBC, DOC and EOC were significantly correlated with TOC, and their relative coefficients increased with the advanced succession stages of the studied forests. All the coefficients were higher in the secondary growth forests than in the Chinese fir plantations. (4) In the four forest types, TOC, MBC, DOC and EOC had a significant correlation with soil total N, available N, total P, available P, total K and available K.