Abstract: In this paper we give a method to raise the resolution of some narrow frequency domain-band, it is called ZOOM-FFT1,and we implement it on the computer. We affirm the superiority of this method on solving to raise the resolution of frequency. At the same time, we also implement the method ZOOM-FFT2 on the computer to raise the resolution of the whole frequency domain-band, we point out it's applicable region. According to these two methods, we program two subroutines, which can use small capacity FFT analyzer to dispose of large capacity input data, and can give different spectral lines of resolution power spectral function and correlation function.