On the basis of the Fourier optics, we ve analysed the optical far-field of a laser beam passing through the UHF acoustic standing waves and found that there is temperal spectrum in the spatial spectrum on the far-field plane besides the spatial spectrum. In accordance with the above results we ve developed an imaging principle of UHF acoustic standing wavefronts: by temporal crosscorrelation, the non-zero Value of correlation of the same temporal frequencies in the different spatial frequencies is obtained. Therefore we have not only clarified the confusion of the theory but also developed a new method for imaging the UHF acoustic st anding wavefronts. And the results have been proved experimehtally.