Abstract: The principle of dynamic detection and methods of elastic wave computerized tomography(CT) are introduced. The P-wave velocity, whose changes reflect the stress states, the changes in structure and the failure degree of rock mass, is used as an inversion parameter. The revisional simultaneous iterative reconstruction technique(SIRT) is applied to inversion. The dynamic detection trial of rock mass failure at different mine stages in coal mine is made by acoustic wave CT. The results indicate that the elastic wave tomography can detect the rock mass failure dynamically in high accuracy and high resolution.