Abstract: It is necessary to improve plough layer for solving the problems of shallow and compacted plough layer and plough layer lack, which are caused by a long-term single rotation and shallow tillage. In order to examine the effects of different tillage practices on soil organic carbon contents and storages, soil organic carbon stratification ratio of cultivated land, four single tillage treatments and two rotational tillage treatments were conducted including conventional tillage (CT), rotary tillage (RT), subsoiling tillage (ST), no tillage (NT) treatment and conventional tillage -no tillage (CT-NT), subsoiling-no tillage (ST-NT) in Gansu Yellow River irrigation district on continuous 8-year-tillage cornfields from 2014 to 2017. The results showed that the 0-40 cm layers organic carbon contents and storages of continuous no-tillage (NT) were significantly increased by 4.45% and 5.27% compared with CT, 7.23% and 8.50% compared with RT. Continuous subsoiling tillage (ST) also had a good carbon sequestration effect, second only to NT in four single tillage practice, the organic carbon contents and storages were significantly increased by 2.28% and 4.03% compared with CT, 3.52% and 7.22% compared with RT. Continuous conventional tillage (CT) and rotary tillage (RT) both significantly reduced soil organic carbon contents and storages, the decreases of soil organic carbon contents and storages were 2.79%, 2.32% and 1.18% , 0.62% respectively, and the reduction of RT were greater than CT. The two rotational treatments of CT-NT and ST-NT both had good carbon sequestration effect, and also accorded with the local farmers operating habits, the organic carbon contents were significantly increased by 2.44% and 4.82% compared with CT, and 5.12% and 7.55% compared with RT respectively, and the organic carbon storages increased by 2.50% and 5.47% compared with CT, and 5.64% and 8.70% compared with RT. The soil organic carbon were stratified by different tillage practices, the stratification of SR·Cc(stratification ratio of organic carbon content )showed significant difference from the first year, but the stratification of SR·esm (stratification ratio of organic carbon storage)came to this until the third year. The stratification of organic carbon contents were more manifested in different soil layers, the mean values of SR3 and SR2 were respectively higher 29.12% and 9.32% than those of SR1(The ratio of organic carbon content in soil layer of 0-10 cm to 10-20 cm), but there were little change between treatments at the same level. However, the organic carbon storages were stratified only below the topsoil, the mean value of SR2 (The ratio of organic carbon storage in soil layer of 0-10 cm to 20-30 cm)same as SR1, but SR3 (The ratio of organic carbon reserves in soil layer of 0-10 cm to 30-40 cm) was higher 17.82% than SR1. Moreover, the stratified characteristics were obvious among the same layers, RT was significantly lower and NT was significantly higher than other treatments at the same level. We consider the most typical reason for this situation was the soil bulk density between different tillage treatments in calculating the SR·esm. As for which calculation method can better represent the stratification characteristics of soil organic carbon, more in-depth research is needed. Therefore, any single tillage measure has its limitations, and the two rotational tillage treatments of CT-NT and ST-NT are ideal tillage practices, which had certain application value in this regional agricultural development.