The invention discloses a wavelet packet conversion based frequency spectrum imaging method. The method includes steps of performing encrypted wavelet packet conversion on a three-dimensional seismic data volume subjected to offset and dissolving seismic record into frequency-dividing seismic record ranked according to frequency band size from small to large; calculating five three-dimensional attribute data volume including frequency-dividing instantaneous amplitude spectrum, frequency-dividing instantaneous phase spectrum, instantaneous average frequency, instantaneous bandwidth and instantaneous absorption coefficient according to the wavelet packet conversion result; performing attribute slicing under the control of a seismic interpretation layer. According to the invention, influence on seismic wavelet spectrum estimation due to reflection coefficients is eliminated through a complex cepstrum technology, so that the instantaneous absorption coefficient estimated on said basis is more reasonable. A target is made prominent by utilizing a specific effect of color mixing in integrated display of three different frequency attributes and the target distinguishing effect of single frequency can be improved effectively.