[Objective] In response to the controversy over the "source-sink" effects of hydraulic erosion on soil carbon cycle, the impact mechanism of hydraulic erosion on soil organic carbon mineralization and soil microbial diversity were reviewed and the directions and precautions of quantitative research in this field in the future were presented. [Methods] Based on the conception and theory of "source effects" and "sink effects" of hydraulic erosion on soil carbon cycle, the core issues of the current controversy over the "source-sink" effects of hydraulic erosion on soil carbon cycle were analyzed, and then the differences of soil microbial diversity changes among different types of soil microorganisms caused by hydraulic erosion and their mechanisms were discussed. [Results] The "source effects" of hydraulic erosion on soil carbon cycle were mainly caused by the organic carbon mineralization during erosion progress, while the "sink effects" were mainly caused by the migration of soil organic carbon to the low-lying areas for sequestration during deposition process. The respiration and decomposition of soil microorganisms resulted in the disappearance of carbon "sinks" in the soil carbon cycle. Hydraulic erosion process weakened the complexity of bacterial community structure, while the deposition process increased the complexity of bacterial community structure. However, both erosion and deposition processes weakened the α-diversity and the structure complexity of fungal community. Hydraulic erosion process indirectly impacted soil microorganisms diversity mainly through altering the soil organic carbon content, vegetation cover and soil pH. [Conclusion] Further research should strengthen the quantitative research on the influence mechanism of hydraulic erosion process on soil carbon cycle at different scales, the interaction mechanism between hydraulic erosion process and soil microbial diversity, as well as the influence mechanism of soil microorganisms on soil carbon cycle during hydraulic erosion progress.