This paper is aimed at investigating the acoustic properties of rock mass under the three-dimentional different stress states, and is presented to discuss emphatically the characteristics of the acoustic wave propagation and the stress-velocity relation in both rocks (sandstone and limestone) under uniaxial and true triaxial compression. The results indicate three regions in which the acoustic velocities and the strains change with the stresses are approximately similar under different stress states; and the acoustic velocity-stress relations for elastic rocks may be represented by different interdependence coefficients under uniaxial compression. At a time, The acoustic measurement method of rock mass stresses and the horizontal tectonic stress are discussed.