Abstract: In the design of FFT based on FPGA, in order to increase FFT processing speed, this paper bring forward a new method that use shift-register to store twiddle-factors, and validated on Stratix series FPGA of Altera company. Experimentation result indicates that this method can improve FFT processing speed of FFT observably than the method of store twiddle-factors with ROM generally, and can satisfy FFT real-time processing request better.