In order to explore the response of interception and sediment reduction effect of grass-based vegetation filter strip to incoming water flow and sediment concentration, different incoming water flows (0.77, 0.9, 1.08, 1.26 L/s) and sediment concentrations(0.04, 0.06, 0.08, 0.1 g/cm³) were set up in a agro-pastoral ecotone in the central Inner Mongolia. The effect of river closure and sediment reduction of stem spacing in vegetation filter strip under different inflow conditions was studied. Based on VFSMOD model simulation, the relevant parameters of vegetation filter strip in this area were optimized. The results showed that VFSMOD model could well predict the sediment and runoff yield in the filter strip of agropyron cristatum and Leymus chinensis. The runoff interception of vegetation in the early stage mainly depended on soil infiltration, and the runoff outflow time was shortened with the increases of inflow intensities. The outflow time of 0.77 L/s inflow intensity was 1.3, 1.6 and 1.6 times of 0.9, 1.08 and 1.26 L/s. The sediment discharge under 0.77 and 0.9 L/s tended to be stable, while the 1.08 and 1.26 L/s increased with time. The inflow sediment content and inflow intensity have significant influence on the outflow sediment quantity (p<0.05).