The invention discloses a seismic data frequency broadening method for frequency domain signal aliasing. The seismic data frequency broadening method comprises the steps of: S1, performing spectrum analysis on a seismic signal firstly, determining a main frequency band range of the seismic signal, then determining a fundamental wave frequency range to be selected when calculating harmonics, and determining a fundamental wave frequency range to be selected when calculating subharmonics; S2, performing wavelet analysis calculation on the seismic signal by utilizing continuous wavelet transform,so as to obtain a wavelet domain seismic signal, namely, a seismic fundamental wave signal used for calculating harmonic signals and subharmonic signals; S3, calculating amplitude spectra of the harmonic signals and the subharmonic signals according to an amplitude spectrum of the seismic fundamental wave signal, wherein phase spectra of the harmonic signals and the subharmonic signals maintain anoriginal phase spectrum of the seismic fundamental wave signal; S4, aliasing the harmonic signals and the subharmonic signals obtained through calculation by using the amplitude spectra and the phasespectra into a frequency spectrum of an original seismic signal to achieve the frequency band broadening purpose, wherein signal energy of the harmonic signals and the subharmonic signals needs to beadjusted in the process, such that energy of the harmonic part obtained through calculation is balanced with energy of the original seismic signal; S5, and adding a predicted signal back to the original signal.