[Objective] The remediation effects of biochar on eroded mollisols aggregates, define the influence mechanism of biochar on eroded mollisols aggregates were determined in order to provide a scientific basis for remediation of eroded mollisols. [Methods] Four experimental treatments were imposed to determine the effects of biochar on aggregates of an eroded mollisols: uneroded farmland as the control treatment (CK); uneroded farmland with biochar application (CK+BC); simulated eroded soil (RS); and biochar added to eroded soil (RS+BC). [Results] Biochar application increased the content of 0.25～2 mm size aggregates by 14.01% in CK+BC compared with CK. The content of 0.25～2 mm size aggregates in RS+BC treatment increased by 12.11% compared with RS. In addition, biochar increased the geometric mean diameter (GMD) and the contents of macro-aggregates (R_0.25), and the concentration of soil organic carbon (SOC) in bulk soil and aggregates larger than 0.25 mm. These results indicated that biochar improved the SOC content by increasing its macro-aggregates. GMD was positively and negatively correlated with the concentrations of SOC and exchangeable sodium, respectively. However, the function of SOC in aggregation was larger than function of exchangeable sodium in dispersion, resulting in improved aggregate stability. [Conclusion] Biochar improves the structure of eroded mollisols, promotes soil aggregation, and has a good remediation effect on the eroded soil, and is therefore an effective strategy to remediate eroded soil.