The characteristics of soil organic carbon (SOC)decompositions and the carbon pool sizes and turnover rates of active carbon pool,slow carbon pool and passive carbon pool under different vegetations and Chinese fir plantation of different forest ages are discussed. The results indicate that the general trend is there is a faster decomposition rate in the first incubation period than in the second period and in the surface soil than in the subsoil.In the surface soil,effect of decomposition rate on different vegetations is broad leaved forest>mature Chinese fir plantation and on Chinese fir plantation of different forest ages is midaged forest>mature forest>young forest.In the subsoil,there is a few differences on decomposition rate and culmulative amount of carbon mineralized under different vegetations;Effect of culmulative amount of soil organic carbon mineralized on different vegetations and Chinese fir plantation of different forest ages is the first month>the second month>the third month, the surface soil>the subsoil.In the surface soil,the effect is midaged Chinese fir plantation > broad leaved forest >mature Chinese fir plantation >young Chinese fir plantation;There is a different carbon pool sizes and turnover rate of activecarbon pool, slow carbon pool and passive carbon pool under different vegetations and Chinese fir plantation of different forest ages,the active pool(Ca)comprised 1.70% to 4.98% of the SOC in the surface and subsoil with an average field mean residence time(MRT) of 10 to 23 d,the slow pool comprised 16.21% to 49.52% of the SOC ,they had field MRT of 0.8 to 13.1 year,the passive pool comprised 46.22% to 80.50% with a assumed field MRT of 1 000 year.