Abstract: Riparian buffer play an important role in improving and protecting water quality from non-point source pollution. Understanding the riparian structure and width is critical for its function and management. In this study, the selected natural buffers were in the Dongzhanbei River basin in Danyang city. The effects of four vegetation types and two kinds of vegetation width(3 m and 6 m)on TN, NH⁺₄-N, TP and COD removal were assessed respectively. The results indicated that vegetation types had significant effect on pollutant’s removal and the removal ratio varied with different seasons, vegetations and pollutants. The removal values of shrub-herb buffer for these four pollutants were higher than the other three vegetation types all through the year. In summer and autumn, the removal rate of riparian buffer with reed was the highest, while it was the lowest in winter. It was also demonstrated that the pollutant removal rates of riparian buffer with arbor- shrub-herb were higher than that of arbor-herb. The removal efficiency of pollutants for different buffer widths varied with seasons, vegetation and pollutant types. And it was higher in winter than in summer, for TN than for TP, and for arbor-herb than shrub-herb. Overall, the removal rates of the four vegetation types were changing with 20%-40% for TN, 20%-70% for NH⁺₄-N, 50%-90% for TP and 40%-80% for COD.