Abstract: Litter coverage maybe significantly affect hydrodynamic characteristics of overland flow. An artificially simulated rainfall experiment was carried out to investigate the effects of litter coverage of different species and mass of different levels on the overland flow hydraulic parameters with a bare slope as the control. There seven litter mass coverages and two rainfall intensities in the experiment. Typical grassland litter of Artemisia gmelinii with the composite family and Bothriochloa ischcemum (Linn.) Keng. with the grass family were selected in the Loess hilly-gully region, the north of Shaanxi province, China. Seven litter mass coverages were set to Artemisia gmelinii and Bothriochloa ischcemum (Linn.) Keng., respectively, varying from 100 to 1 000 g/m2 and 50 to 600 g/m2 for each of those vegetation types and subjected to simulated two rainfall intensities: 60 and 120 mm/h. A normal rainfall intensity 60 mm/h and a rainstorm rainfall intensity 120 mm/h as the simulated rainfall intensities. According the extreme rainstorm event “7•26” in Zizhou and Suide, the north of Shaanxi province which the maximum hourly rainfall was 52 mm, so 60 mm was set to simulate rainfall. During the rainfall experiment, flow velocity and runoff were measured every three minutes, the water temperature was measured every fifteen minutes, and the Reynolds number, Froude number and the resistance coefficient were calculated based on flow velocity, flow discharge or water temperature. The results showed that compared with bare slope control, the flow velocity, Reynolds number and Froude number of litter coverage treatments were reduced by 77.3%, 18.5%, and 87.4%, respectively. However, the resistance coefficient was 314 times greater than the reference treatment. The average flow velocity, Reynolds number and Froude number decreased with the litter mass coverage increased as a power function (P<0.01), however, the resistance coefficient increased with a power function (P<0.01). As a whole, with the litter mass increased, the flow velocity, Reynolds number and Froude number of Bothriochloa ischcemum (Linn.) Keng. were larger than that the Artemisia gmelinii (P<0.01), but the resistance coefficient was opposite. The stepwise regression results showed that there was a significant (P<0.01) power function relationship between flow discharge, litter mass coverage, characteristic parameters of litter and the hydraulic parameters of the slope (P<0.01). The R2 and NSE (Nash-Sutcliffe efficiency coefficient) ranged from 0.84 to 0.92 and 0.60 to 0.91, respectively. In addition to the flow discharge and litter mass coverage, the litter density was the key parameter to affect the flow velocity. Furthermore, the projected area of litter and the flow pattern had a close relationship, and the litter surface area was the main parameter for characterizing the resistance coefficient. This study can reveal the soil and water conservation mechanism of grassland litter and correctly evaluate the soil and water conservation benefits of grassland.