Abstract: The elastic wave velocity test of rock specimen is one of important tasks in the assessment of rock mass quality. It must make the most of information contained in the waves to understand the dynamic elasticity of the rock by the means to draw the ultrasonic wave propagation in the rock specimen, and seismic phase analysis is a powerful useful information in the waves. Based on the seismic phase analysis, the identification of seismic phase and the revise of its travel time are stressed in this paper. Applying the ultrasonic method, a good result is obtained in the quality assessment of the rock mass in a project.