The storage and dynamics of soil organic carbon (SOC) under different forest types is one of the important concerns of global change. We determined the seasonal (dry and wet seasons) and spatial (0 - 10, 10 - 20 and 20 - 40 cm depths) variations of SOC under six forest types (Shrub-grass forest, SF; Masson pine forest, PF; Eucalyptus forest, EF; Native-species forest, NF; Acacia forest, AF; Monsoon evergreen broadleaved forest, MF) in Heshan, southern China. Carbon recalcitrant indexes (RIC) and its relationships with total available nitrogen (TAN) in soils of the forest types were also detected. The results showed that: 1) the contents of SOC under 6 forest types were higher in wet season than in dry season with a declining trend with the increase of soil depth, SOC content was highest in AF while lowest in PF and SF; 2) 0 - 10 cm depth soils had highest proportion of SOC storage (more than 40%) for 0 - 40 cm depth soils; 3) RIC decreased with increase of soil depth. The higher contents of Alkyl-C and ROC in MF, NF and AF than in EF and PF implied that SOC in the former three forest types had higher stability; and 4) SOC contents significantly positively correlated with soil TAN contents in all forest types. The results suggested that in the process of vegetation restoration, the selection of legume species coupled with native species constructing evergreen broadleaved forest would improve potential carbon sink of forests.