Abstract: Elastic wave tomography technique, short for "elastic wave CT scanning". As is known, there is a linear integral relationship between the travel time and amplitude of the elastic wave ray propagating through stratum and some physical parameters of the stratum. By using this key characteristics, elastic wave CT scanning can retrieve 3d velocity structure and attenuation characteristics of strata on the premise of no damage to the object. In this paper, based on the elastic wave CT technique, through the inversion of the rock mass slowness between holes and synthesizing the drill core record and engineering site situation, fractures development of Banbi Mountain in Chengde City was interpreted, the location and size of the risk rock mass fractures were determined. It is proved that fractures position detected by the elastic wave CT technique is consistent with the situation in the field after drilling, which provides basis for the comprehensive improvement of the risk rock mass.