Abstract: Soil erosion is divided into three subprocesses of soil detachment,sediment transport,and sediment deposition. Exploring the critical conditions in terms of hydraulic,topography,soil as well as near-surface characteristics for the occurrence and development of these processes is the basis of establishing process-based soil erosion model and then accurately predicting soil erosion. Hence,the paper summarized the main factors that influencing soil detachment process by overland flow and its mechanism in respect to overland flow hydrodynamics,soil properties,near soil surface characteristics,and spatial-temporal variability of soil detachment. Finally,main problems requiring deep exploration in future are recommended from six aspects,i.e. the spatial-temporal scale of study on soil detachment process,the dynamic mechanism of soil detachment process,the influencing mechanism of rill morphological evolution and network structure on soil detachment process,the coupling mechanism of soil detachment and sediment transport,the measuring method and criterion of soil detachment,and the obtaining and predicting soil erosion resistance parameters. The paper is conducive to deepening the understanding of soil detachment process by overland flow. Additionally,it provides valuable references for the correlational studies of soil erosion process and establishment of process-based soil erosion models.