Abstract: Gammatone Filter Bank (GTFB) is perfectly suitable for speech processing systems like digital hearing aids, speech enhancement and speech recognition system. However, the high computational complexity and non-real-time characteristic in the hardware synthesis restrict its practical application. In this paper, an efficient core computation unit structure is proposed. Besides, a low complexity synthesis algorithm is proposed and the real-time characteristic is achieved by compensating the filter delay. The measurement results verified show that a 128-band high-efficient real-time reconfigurable Gammatone Filter Bank is realized in FPGA. The design has only 20 ms delay and improve the dual-microphone CASA speech enhancement system performance.