Abstract: The hybrid membrane bioreactor（HMBR）was designed by using the new biofringe (BF) filling combined with A/O system. The BF biofilm was with dynamic natural cultivation and continuous water seepage, and the pilot-scale starting-up tests were carried out for treatment of acrylic fiber wastewater. The results showed that the system biofilm could be hung effectively and rapidly, with short starting-up time and stable system operation. The BF filling took good effects on adsorbing the activated sludge in the reactor. After the biofilm was hung stably with the HRT controlled at 36 h, the nitration liquid return rate at 100% and the influent flow at 600 L/h, the water quality after treatment proved to be stable and the effluent ammonia-nitrogen concentration was under 5 mg/L, better than Grade 1 of the National Standard of Acrylic Fiber Industry (15 mg/L), and the average removal rate of the total nitrogen could reach 55.86%, which demonstrated that the system had good denitrification ability. The membrane interception had certain effect on the chemical oxygen demand (COD_Cr) removal but no effect on ammonia-nitrogen removal. Also, the simultaneous nitrification-denitrification (SND) occurred in the reactor.