To investigate the effect of hydrodynamic conditions on hydraulically irreversible fouling of UF membrane in MBR for treating micro-polluted water, the method of determination of hydraulically irreversible fouling of UF membrane was introduced, and the effects of aeration, backwashing, flux and temperature on irreversible fouling were discussed. The results showed that the pollutant removal of MBR should be taken into account when selecting the time and flow of aeration. The duration of 2 min was necessary during intermittent aeration, with the optimal aeration intensity of 30-36 m³／(m²·h). Prolonged backwashing duration was found to control the hydraulically irreversible fouling. The production of UF membrane in MBR should also be considered when determining the proper backwashing duration. The permeate fluxes influenced the hydraulically irreversible fouling rate significantly, and the values of PVDF and PVC membranes should be no more than 31.5 and 14.0 L／(m²·h) to maintain the long-term stable operation. Meanwhile, the impact of temperature on irreversible fouling should be considered.