Abstract: Soil active organic carbon (AOC) is a critical component of soil organic carbon (SOC). Although it accounts for a small proportion of SOC, it is susceptible to soil management practices and changes rapidly, making it an important indicator for assessing soil quality dynamics. This study was based on an 8-year field experiment at the Hailun Station, involving different tillage methods and straw return treatments. It systematically explored the effects of tillage practices and straw return rates on the contents and efficiencies of active carbon fractions, as well as their influence on the carbon pool activity and comprehensive fertility of black soil. Soil fertility and carbon pool quality were evaluated using the Integrated Fertility Index (IFI) and Carbon Pool Management Index (CPMI). The results show that, compared to the CTS0 treatment (conventional tillage at 20 cm depth with no straw return), all treatments with varying tillage practices and straw return rates significantly increase the contents and efficiencies of SOC, total nitrogen (TN), dissolved organic carbon (DOC), and microbial biomass carbon (MBC) (P<0.05). Among these treatments, CTS2 (conventional tillage at 20 cm depth with full straw return at 10 t·hm⁻²) demonstrates the most pronounced effect on improving soil fertility, increasing SOC and TN contents by 13.7% and 18.9% respectively, and raising the IFI value by 7.7%. The CTSA treatment (conventional tillage at 20 cm depth with full straw return at 10 t·hm⁻² after straw burning) results in a 12.3% increase in SOC content, with significant increases of 18.9% in DOC and 31.6% in MBC contents, along with a 12.5% improvement in CPMI. Additionally, IFI shows significant positive correlations with SOC, TN, available phosphorus (AP), available potassium (AK), DOC, and MBC (P<0.05). Similarly, CPMI is significantly positively correlated with DOC, MBC, and easily oxidizable organic carbon(P<0.05), indicating that the enhancement of active carbon fractions directly influences soil carbon pool stability and management outcomes.