In order to study the fracture evolution characteristics of white sandstone under uniaxial compression loading, the spatial energy distribution of acoustic emission (AE) waveform is applied to determine the fracture direction of rock. Through the three-dimensional AE monitoring test of white sandstone with prefabricated crack, the energy spectrum of waveform from each channel was obtained by short-time Fourier transform (STFT). The microfracture direction was represented by direction of the channel with the minimum energy to that with the maximum. The fracture length was calculated by magnitude of the channel with maximum energy. Thus the AE vector of microfracture was obtained. The results show that fracture propagation directions of white sandstone are mainly parallel to the principal stress direction and the theoretical conjugate shear plane directions. In stages of the initial compaction and the elastic, fissures were mainly in one of the three directions. Starting from the crack deformation section, proportions of fractures in the three directions began to decrease gradually, and tended to be 30% in the pre-peak softening section. It is also found that the AE vector is clustered along the main rupture surface, and a shear zone running through the rock sample is formed in the pre-peak softening section, which may be a reliable critical precursor to rock failure.