Soil erosion and deposition influences accumulation and loss of soil organic carbon (SOC),yet it has never been an issue of proper attention in the study of soil carbon cycle.In this paper,the CENTURY model was used to simulate original organic carbon accumulat ion in black soil of a given soil texture in a typical rolling farmland in the Black soil region,Northeast China to get the initial value of SOC and its fractions;Then the model was verified through statistical comparison between the simulations and actual measurements with and without considering SOC enrichment with sediments;And then temporal variation of SOC and its fractions after reclamation,and contribution of soil erosion to SOC loss were assessed.The results show that SOC accumulation could be divided into two stages,i.e.fast accumulat ion in earlier stage and slow accumulation in later stage.The slow organic carbon accumulation in the former stage contributed the most to the SOC pool and passive organic carbon played a dominant role in SOC accumulation at the latter stage.When equilibrium was reached the content of organic carbon in the black soil in the study area was 7 240 g m^-2,of which slow and passive organic carbon accounted for 97.4%;The simulations tallied better with the actual measurements was better when the effect of sediments on SOC enrichment was taken into account;When natural black soil was cultivated,active and slow carbon was most likely to get decomposed by microorganism and mineralized,while passive carbon was losing with soil erosion.It was not so significant because soil erosion was not serious problem in the study area.