The effect of forage grass on runoff and sediment reductions was studied by using different flows scouring experiment,and analyzed mechanism of regulating runoff in slope from the duration of producing runoff,velocity and depth of runoff.The results showed that:(1) The grass slope had significant effect of decreasing runoff and sediment yield,which,compared with the control,runoff coefficient and sediment yield rate decreased 28.3% and 78.4%,respectively.(2) The generation process of runoff in grass and without grass slope has a similar rule.The process of sediment yield rate in the slope without grass took on the trend of high-low-high,however,for the grass slopes,having a trend of increasing initially and finally apt to steady.(3)Moreover,compared withthe control,time of put off producing runoff in the grass slope is three times of the slope without grass and velocity of runoff decreased 40%,which led to the increase of infiltration rate and the decrease of ability of runoff scouring and sediment yield in grass slopes.(4) The influence of grassland to runoff depth in slope is not apparent,and the variety of runoff depth is difficult to reflect the action of grass to runoff regulation.However,runoff velocity can be more reflecting the effect of grass on soil and water conservation and runoff regulation.