Abstract：Based on the rock mechanical experiment on low porosity and low permeability sandstone under different confining pressures and synchronous collecting experiments of transit time intervals of longitudinal and transverse waves and wave patterns of those rocks，the behaviors of acoustic velocity，amplitude and frequency spectrum properties under triaxial and uniaxial loadings are studied. The following conclusions can be drawn. (1) The velocity and frequency spectrum properties of longitudinal and transverse waves change with rock deformation and failure stages. In the stage of fracture and pore compaction inside rock，the velocities of the longitudinal and transverse waves increase rapidly. The ratio of axial stress corresponding to peak velocity of longitudinal and transverse waves to compressive strength of rock decreases as the arithmetic product of porosity and permeability increases. (2) The changes of longitudinal and transverse waves patterns are closely related to rock deformation. As the axial load increases，the fractures in rock generate and develop；when the axial stress reaches 60% of the limit strength，obvious scattered wave signal appears at the end of the transverse wave pattern. (3) As the axial load increases，rock is compacted，and the amplitude of frequency spectrum curve increases as well. When the axial load increases further，the fractures will appear in rock；and low frequency signal is more active than the high frequency one in frequency spectrum curve. (4) In the stage before rock strength reaches peak value，both the first arrival wave amplitude and the principal amplitude tend to increase. In the stage of elastic compression，the two kinds of amplitudes increase rapidly，while in the stage of unsteady fracture expansion，the principal amplitude tends to increase more slowly than the first arrival wave amplitude. It is of theoretical and practical significance to predict rock fracture and its long-term stability.
