Abstract：Rock samples including slate，biotite gneiss and granite gneiss are desiccated in the condition of 100℃–110℃ and tested by ultrasonic method. These samples are saturated in the vacuum container for 24 hours，and then tested by ultrasonic method again. Based on the synthetic analysis of acoustic wave，wave attenuation and frequency spectrum characters，some conclusions are drawn. The water content percentage in rock samples is 0.100%–0.212%. The velocities of P-wave and S-wave in rock samples are scarcely varied under water-saturated and dry conditions. The P-wave attenuation decreases when dry samples are water-saturated，on the contrary，the S-wave attenuation increases in the same case. Different rocks appear different attenuation anisotropy characters；and the wave attenuation anisotropy in slate and biotite gneiss is observed under dry and water-saturation conditions. However，such phenomenon has seldom been found in granite gneiss. The wave base frequency gets lower when rock samples are water-saturated. The waves are decomposed by db1 wavelet packet at the third level and the energy of different frequency area is calculated. It is found that，when dry rocks are water-saturated，the P-wave energy proportion of the lowest frequency part increases；but the energy proportion in higher frequency part decreases.
