This study was conducted to research the soil organic carbon contents in terraced fields.216 topsoil samples were collected from the fields growing four local crops(mung bean,millet,sorghum,corn) ,and soil organic carbon contents of these four different soil samples and its affecting factors by the way of difference analysis were analyzed.The results showed that the average value of the topsoil organic carbon contents in the terraced fields was 6.34 g/kg,which was at the lower middle level.Under different crops,soil organic carbon content expressed from high to low as mung bean>millet>sorghum>corn.On the 0.01 level of significance,soil organic carbon content of mung bean was significantly higher than those of millet,sorghum and corn（P=0.000 6）.Soil organic carbon contents of corn,sorghum and mung bean were reduced with the rising slope position,for millet it was the opposite.Organic carbon contents of all four crops among two slope directions expressed as shade slope>sunny slope.Mung bean was beneficial for the fertility restoration of the soil.Lower slope position and shade slope had relatively high organic carbon content.Effects of human activities on soil organic carbon content of terraced fields were embodied in the different cultivation and management measures,notill methods， straw returning and planting mung bean were helped soil organic carbon content increasing.