Abstract: Soil organic carbon (SOC) pool plays an important role in mitigating greenhouse gas (GHG) emissions. However, long-term conventional tillage practices can result in significant losses of soil organic matter (SOM), thus inducing an increase in soil erosion and increasing CO2 efflux. In addition, burning straw is another important emission sources of GHG in the North China Plain (NCP). In order to identify the best tillage practices for SOC sequestration under the wheat-maize cropping system in this region, we investigated the effects of tillage on SOC concentration, SOC stock, the carbon pool management index (CMI), and SOC distribution in the soil profile. This study was conducted at the Wuqiao Experiment Station in Hebei Province from 2008. Five different treatments were established, including no-till without straw retention (NT0), conventional tillage without straw retention (CT0), no-till with straw retention (NT), conventional tillage with straw retention (CT), and rotary tillage with straw retention (RT). Soil samples were taken after harvesting of wheat, and soil bulk density (BD), SOC, and labile organic carbon (LOC) were analyzed. The results showed that NT0 significantly increased BD in all soil layers (0~50 cm) (P<0.05). Concentration of SOC decreased with an increased depth (0-110 cm) among all treatments. NT significantly increased the SOC concentration at the topsoil (0-10 cm) compared with the other treatments. Concentration of SOC under NT was 34.4% higher than that under CT0 at 0-5 cm depth. However, SOC under NT was lower compared with other treatments (except NT0) in >10-50 cm, but there was no significant difference among the treatments deep layers (>50-110 cm). The relationship between BD and SOC concentration showed a strong negative correlation. In order to reduce the bias caused by variations in bulk density under different tillage treatments, the equivalent soil mass method was used in calculating SOC stock. At the depth of 0~30 cm, the total SOC stock under NT was the highest (40.73 Mg/hm2) among all the treatments, and there was no significant difference in SOC stock between CT and NT, but those were 13.1% and 11.0% higher than CT0, respectively. However, for the 0-50cm depth, the SOC stock in CT was highest, but no significant difference with NT (P<0.05). Compared with CT0, NT0 reduced the LOC concentration in all soil layers, but NT increased at 0-10cm soil layers. The carbon management index (CMI) under RT were 21.7 % and 32.3% higher than NT at 0-5 and 5-10 cm depth, respectively, but no significant difference occurred at both >10-20 cm and >20-30 cm. However, CMI under CT was higher than that under NT, NT0 and CT0 at all soil depths. Results of that indicated that crop straw retention could increase soil quality and increase CMI that was also strongly affected by tillage management. In conclusion, NT reduced soil disturbance and increased the input of SOM, which was beneficial in SOC storage, especially at the surface layers. Nonetheless, the results of this study were based on short-term tillage experiments in SOC concentration/stock. Therefore, a long-time study may reveal the changes in SOC and its mechanism under conservation tillage because of the duration effects. These data also suggest sampling subsoil layers to understand the underpinning processes governing SOC sequestration.