Water erosion process is the interaction between erosion force of rainfall and runoff and soil resistance under the various factors, especially the vegetation plays a signification role, therefore, a better understanding of the effects of different raindrops and runoff characteristics on soil detachment of ground cover hillslope is basis to research soil erosion dynamics processes. A slope soil detachment experiment was conducted to reveal the slope erosion dynamic mechanism of herbs coverage. There erosion plots (0.5m wide×2m long) which were composed of upslope sink (1.5m long) and downslope soil box (0.5m long) with average coverage of 0, 20%~30%, 50%~60% and 80%~90% were installed. In order to research the quantitative influence of herbs structure on soil detachment rate and erosion dynamics, the experimental treatments separately measured the detachment effect of rainfall and runoff on slope soil. The results showed that the effect of herbs structure on soil detachment was different, and sediment reduction rate of roots was higher than the canopy （P<0.05). For two kinds of experimental herbs, the raindrops retardation coefficient of Artemisia carvifolia canopy is higher than that of Setaria viridis (L.) Beauv. canopy（P<0.05), and the sediment reduction effect of roots is the opposite, the sediment reduction rate was decreased by 57.79%~74.74% and 62.87%~81.21%, respectively. This is mainly related to leaf area index and fibrous root content, and root length density and soil detachment rate present index function relation. Comparing with the soil detachment resistance characteristics, for the slope of herbs coverage, granule resistance and wave resistance were increased with the increasing vegetation coverage. The slope soil detachment dynamics mainly includes the rainfall and runoff, the herbs coverage on the influence of rainfall and runoff erosion dynamics are 189.21~698.92J·mm/(m2·min) and 6.27~20.38kg/(m·s2), respectively. The reduction coefficients were 22.75%~84.04% and 19.68%~63.97%. This study reveals the important effect of ground cover on soil detachment from dynamic mechanism, aimed to provide basis research on the hillslope erosion dynamics.