Aiming at the contradiction between the resolution and range of synthesis frequency and the phase noise problem which affecting the frequency stability. A method of frequency synthesis based on two-stage fractional frequency division phase locked loop was proposed. This method realized high resolution characteristic by the former fractional frequency division phase locked loop. The latter fractional frequency division phase locked loop not only realized the extension of the output frequency range but also suppressed the phase noise. The narrow-band phase-locked loop filter between two-stage fractional frequency division phase locked loop isolated the noise of the former Fractional-N phase-locked loop, and the phase-detection frequency of the narrow-band phase-locked loop filter is switched according to the decimal part value of the latter Fractional-N phase-locked loop’s dividing ratio, thereby suppressed the fractional spuriousness.