Abstract: In order to find out the tolerance ability of grass buffer on shock load from agricultural runoff pollutant, the effect of shock load of high concentration on the removal efficiency of riparian buffer on agricultural runoff pollutants were investigated by engineering-scale fields test on site. The results showed that under shock load of high concentration pollutant, grass buffer had good removal efficiency on runoff SS(suspended solids), the concentration of SS showed the same downward trend, fasted at the front, then gradually slowed down, the concentration of SS at end were both under 90mg/L for 2 kind of concentration load, which indicated that high concentration load had no significant effect on the removal of agricultural runoff SS. Buffer had certain purification ability on runoff nutritional pollutants under the impact of high concentrations load, the end removal ratio of runoff TN (total nitrogen), NH4+-N (ammonia nitrogen), TP (total phosphorus) removal was 23%, 16% and 26% respectively, accounted 59%, 55% and 70% for which under common concentration load. It suggests that Bermuda grass buffer had certain purification ability on TN and TP in seepage water, the concentration variation of which had the same trend under two kinds of concentration, Which had no significant difference (p>0.05), and the TP removal rate was slower than TN. The research provides a scientific basis for the optimal designation, maintenance, management and application of riparian buffer.