The long-term effects of different tillage practices on soil organic carbon accumulation and transformation in the black soil remain poorly understood. This study aims to fill this knowledge gap by examining how various tillage methods affect soil carbon content over time, with a focus on the implications for soil health and agricultural sustainability. Based on a long-term field experiment of fallow crop rotation (including three zones: crop zone, fallow zone, and mulch zone), conventional tillage, and no-tillage, the variation characteristics of soil organic carbon (SOC) and its different components, including dissolved organic carbon (DOC), readily oxidizable carbon (ROC), light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were investigated. The results showed that: The contents of SOC and its components decreased with the increasing of soil depth, with no significant differences in SOC and component concentrations observed among the 20-40cm soil layer across all treatments. This suggests that the upper soil layers are more dynamic in terms of carbon cycling and are more influenced by tillage practices. The SOC contents in the 0-20cm soil layer for fallow crop rotation was 17.33%-21.57% higher than those of conventional tillage and no-tillage. The ROC and DOC contents in 0-20cm soil for crop zone of fallow crop rotation and no-tillage were high, whereas POC and LFOC contents in fallow zone of fallow crop rotation were high. T Fallow crop rotation significantly enhanced the increase in POC content in the 0-10cm soil layer, with less effect on subsoil, and it increased LFOC content across all soil layers to varying extents. The POC/SOC and LFOC/SOC for the surface soil layer of the fallow crop rotation were all higher than those in the conventional tillage, indicating the straw mulch was helpful to optimize SOC component composition. There were significant correlations between SOC and ROC, DOC, POC, MAOC and HFOC (P < 0.01) and LFOC (P < 0.05), indicating that the active organic carbon components were significantly affected by SOC and tillage methods. These correlations suggest that tillage practices not only influence the total SOC content but also affect the dynamics of different carbon pools, which can have long-term implications for soil carbon storage and nutrient cycling. Fallow crop rotation and no-tillage methods could significantly increase the active organic carbon contents in 0-20cm soil layer and improve the proportion of SOC component structure, thereby contributing to the accumulation of available soil nutrients.