Abstract: Now, there are two methods to improve the spectral resolution, which are the Band Selected Fourier Analysis and the Digtal Frequency Moving Lower Pass. But on the formulation Δf=1/(NΔ)(N is-sampling data number, Δ is the sampling time interval), increasing Δ can reduce the spectral resolution Δf, increasing N can cut dow Δf too. This paper introduces a new method that does not increase the sampling data number N, but selects the frequency range on the spectral, which is interested, as the input of FFT. the output of FFT is added zeros as the inverse FFT's input, the result is the spectral that is amplified two times. We can obtaine any times amplified spectral by using process above. This method will be found widely use in the correlation spectral analysis of several signals.