Abstract: In order to remove pollutants from river water in a small watershed and restore the ecological function of the water body, a pilot scale test was carried out with modified hollow fiber membrane aerated biofilm for about 100 days. When hydraulic retention time (HRT) was about 8-10 h, the degradation load of ammonia nitrogen per unit membrane area of aeration membrane was 0.65-1.85 g·m^-2·d^-1, and the degradation load of COD per unit membrane area was about 6-10 g·m^-2·d^-1. The TP removal load was 0.05-0.10 g·m^-2·d^-1. The fluorescence index F_I of upstream and downstream in pilot section were 1.82 and 2.12, and B_IX were 0.946 and 1.104, respectively; The freshness index (β: α) were 0.897 and 0.99, respectively. The experimental results show that the membrane aerated biofilm technology had a good removal effect on the main pollutants of river water, which was helpful for the restoration of river ecological functions. It can be used for the pollution control of low-velocity rivers and black and odorous water bodies.