Abstract: Vegetative filter strips can effectively reduce nitrogen and phosphorus load or concentration from agricultural land to surface water. However, the efficiency of vegetative filter strips vary with soil, hydrology and vegetation condition in different rainfall-runoff cases through long-term monitoring, so it is important to assess retention efficiency of vegetative filter strips under single rainfall-runoff condition. Mathematical model is an important tool for the planning and design of vegetative filter strips. Thus, an ease-to-use assessment model is presented to better assess nitrogen and phosphorus retention effect by vegetative filter strips under single runoff condition in the northwest area of China with serious soil erosion. The simplified model proposed involves 3 parts: coupling sub-model, linear correlation sub-model and mixing zone conceptual sub-model. The coupling sub-model of the vegetative filter strips model (VFSMOD) and the modified universal soil loss equation (MUSLE) is made to simulate purification effect of suspended solids (mainly means sediments), because sediment retention efficiency is the combined effect of the sediments entrapped process and the soil erosion or sediments yield process in vegetative filter strips itself. According to significant correlation with sediments and those particle pollutants on runoff, the linear correlation method is used to calculate removal effect of particle nitrogen and particle phosphorus by vegetative filter strips. Infiltration is regarded as the only mechanism to remove dissolved pollutants, namely vegetative filter strips reduce dissolved nitrogen and phosphorus volume by diffusion and infiltration into soil. Therefore, based on mechanism research of the interaction of dissolved pollutants in topsoil and surface runoff, and through simplifying pollutant transport in deep soil, the mixing zone conceptual sub-model is utilized to assess the effect of vegetative filter strips on dissolved nitrogen and phosphorus. Furthermore, the mass dynamic balance equilibrium within overland flow and soil mixing zone is considered accordingly; in overland flow, mass balance includes diffusion, infiltration and soil losses, and in soil mixing zone, it is regarded as uniform mixing and its change covers diffusion and infiltration from runoff, denitrification, leaching, soil losses and adsorption etc. Among them, the coupling model can predict hydrology and suspended solids transport well by considering runoff sluicing impact on sediments from vegetative filter strips in surface soil, and the results show that the relative deviations between simulated and measured concentrations of suspended solids are within ±20%, and the determination coefficients between simulated and measured values is 0.98. The simplified particle nitrogen and phosphorus transport algorithm is presented by the linear correlation method based on field plot experiment data, and the good prediction in runoff and sediments also resulted in good prediction of particle nitrogen and phosphorus transport by vegetative filter strips, since adsorbed nitrogen and phosphorus are the main components of nitrogen and phosphorus in the areas with serious soil erosion. Similarly, the results also show that the relative deviations between simulated and measured concentrations of particle pollutants are within ±20%. It is obvious that a good prediction of dissolved nitrogen and phosphorus is obtained by the mixing zone conceptual model, the input and output of the mass balance system of vegetative filter strips consider biological and chemical processes of dissolved nitrogen and phosphorus in soil mixing zone, and furthermore the detailed analysis and proper simplification for vegetative filter strips system are presented. The relative deviations are within ±20% between simulated and measured concentrations of dissolved nitrogen and phosphorus. Thus, the combined nitrogen or phosphorus modeling approach successfully predicts runoff, sediment, nitrogen and phosphorus transport in the areas with serious soil erosion, which provides the reference for controlling runoff and pollutants transport using vegetative filter strips.