［Objective］ The purification effect of ecological buffer zones （EBZs） on nitrogen and phosphorus pollutants in surface runoff and seepage water under the combined of different internal and external factors was explored to provide an optimized design basis for the control of agricultural non-point source pollution. ［Methods］ The purification capacity of EBZs for nitrogen （TN） and phosphorus （TP） pollutants in both runoff and seepage water was evaluated using an orthogonal experimental design， while two internal factors （vegetation configuration and slope gradient） and two external factors （influent pollutant concentration and flow rate） were investigated， and range analysis was applied to quantify their relative contributions to pollutant removal efficiency. ［Results］ The removal efficiencies of EBZs for TN and TP in seepage water （21.31% and 29.80%， respectively） were significantly higher than those in surface runoff （16.91% and 23.04%， respectively）. Composite vegetation configurations showed better pollutant interception effects than pure herbaceous configurations， with the shrub + herb combination achieving the best results. The average removal rates of TN and TP in surface runoff were 20.16% and 27.24%， respectively， and in seepage water were 24.54% and 33.89%， respectively. Meanwhile， the influence degrees of different internal and external factors on various pollutants varied significantly in EBZs， but generally followed the order： vegetation configuration （most dominant） > influent concentration > slope gradient > flow rate （least influential）. ［Conclusion］ The vegetation configuration has the greatest impact on the pollutant interception capacity of EBZs. However， as the slope， inflow rate， and influent pollutant concentration increase， the pollutant removal rates of EBZs with different vegetation configurations generally show a downward trend.