Abstract: Vegetative barrier-combined filter strips are defined as grass barriers set up before filter strips. They could make concentrated water flow disperse, which exerts the function of grass barriers (i.e., existence of grass barriers improves the performance of filter strips in the purification of pollutants). In this regards, grass barriers are generally considered to be effective in the purification of pollutants when the density of concentrated flow is low, whereas little was known about this effect with an increasing density of concentrated flow. In this study, we constructed Miscanthus floridulus barrier before Vitex negundo filter strip with three densities of concentrated flow (low: one concentrated flow channel; middle: three channels; high: five channels). The aim of work was to identify the effect of M. floridulus combined V. negundo filter strips in reducing nitrogen and phosphorus concentration under three concentrated water flow levels. Our results showed that the combined filter strips had a higher performance in the reduction in the total N, NH₄⁺-N, NO₃^--N and total P compared to those in the V. negundo (P<0.05), regardless of the water flow level. There was no significant difference in the reduction of total N, NH₄⁺-N, NO₃^--N and total P among three water flow levels (P>0.05). We concluded that M. floridulus combined V. negundo filter strips could improve the reduction of nutrients, which couldn’t be influenced by varying density of concentrated flow level.