The effect of N₂ back-flushing period (FT) and time (BT) was compared with the previous result used PES(polyethersulfone) beads loaded with titanium dioxide photocatalyst in hybrid process of alumina microfiltration and PP(polypropylene) beads coated with photocatalyst in viewpoints of membrane fouling resistance (R_f), permeate flux (J), and totalpermeate volume (V_T). The reason of nitrogen back-washing instead of the general air back-washing method is to minimizethe possible effect of oxygen included in air on water quality analysis. As decreasing FT, R_f decreased and J and V_T increased. Treatment efficiency of dissolved organic matters (DOM) was 82.0%, which was the higher than 78.0% of the PESbeads result. This means that PP beads coated with photocatalyst was the more effective than PES beads loaded with photocatalystin the DOM removal. As increasing BT, the final R_f decreased and the final J increased, but V_T was the maximumat BT 15 sec. The average treatment efficiency of turbidity did not have any trend as changing BT. As BT increasing from6 sec to 30 sec, the treatment efficiency of DOM increased 11.8%, which was a little higher than the result of PES beads.