Based on the data from the National Second Soil Survey,this paper analyzed the variation of topsoil organic carbon(SOC) content in cropland and non-cropland,and the difference of SOC content in cropland and non-cropland,paddy fields and upland field among 6 regions.At the same time,the change of topsoil SOC storage led by cultivation was estimated based on the data of SOC content in non-cropland and cropland area.The results indicated that the variation of SOC content in cropland was less than that in non-cropland,and that in paddy field was less than in upland field;secondly,the SOC content in cropland was less than that in non-cropland which decreased 51.5% in average,but that in paddy field was more than in upland field;thirdly,the loss of SOC pool led by the agriculture cultivation was 4.3 Pg,which including the decreasing of paddy field and upland field was 0.67 and 3.63 Pg respectively.At last,this paper analyzed the spatial distribution of the SOC pool loss,and discussed the reason of the most decreasing degree of SOC storage in Northeast and Northern China,which was the much cultivation of soil like black soil,chernozems,and dark brown soil in grassland and wetland,and the irrational agricultural field management.