###### Abstract
[12] found a relationship between fracture extension laws and ultrasonic wave features. [PERSON] et al. [13] conducted an ultrasonic wave test during the break of shale with an imported RTR-1500 rock triaxial device and obtained a variation pattern of ultrasonic wave velocity during shale destruction. [PERSON] et al. [14] tested ultrasonic wave features during sandstone destruction with an RTR-100 testing machine and obtained a relationship between rock dilatancy and S-wave velocity. [PERSON] and [PERSON] et al. [15; 16] found the transmission laws of ultrasonic wave during destruction of sandstone, shale and dolomite and predicted the stability of rock samples based on the variation features of ultrasonic waves. The above research studies were mostly conducted on testing machines with a sonic module added, but these testing machines are expensive and high in terms of test cost. Some of the research studies were conducted by apparatus composed of an ultrasonic wave test device and mechanical testing machine, but the ultrasonic wave was often picked manually in these experiments and are unable to monitor the rock situation in real time. A lot of elastic waves would be produced during the destruction of rock, and sensitive electronic devices are required in order to monitor these elastic waves. Many researchers have studied features of sounds produced by rock samples under tensile, press and shear conditions. [PERSON] et al. [17] conducted uniaxial and indirect tensile tests of layered halite and predicted rock damage based on variations in stress, release of acoustic emission energy and size effect. [PERSON] et al. [18] reached the finding that shale sample with different bedding angles did not change much in tensile strength but differed widely in damage patterns. [PERSON] et al. [19] analyzed the fracture opening situation in the course of a rock straight shear experiment with acoustic emission testing technology. [PERSON] et al. [20] studied the variation laws of AE number, energy, b value and light spectrum during the extension of micro-fissures in a coal sample. [PERSON] et al. [21] evaluated the damage of rock joints in shear experiment with acoustic emission testing technology. [PERSON] [22] examined acoustic emission behavior of fracture extension in gabbro during a uniaxial tensile experiment. [PERSON] et al. [23] improved the discrete element method and proposed and incorporated it in the Universal Distinct Element Code (UDEC) to simulate hydraulic fracturing in heterogeneous rocks. [PERSON] et al. [24] developed a novel analytical model coupling crack propagation in the grout annulus to capture load-displacement performance of cable bolts under axial loading. These research studies provide theoretical foundations for the evaluation of deformation mechanisms and stability of host rocks in underground engineering. Shale gas [25; 26; 27; 28] belongs to unconventional oil and gas resources. With abundant reserves and huge development potentials, the commercial exploitation of shale gas is helpful for eliminating energy shortage. To date, there have been few reports on the method and system of ultrasonic wave monitoring of mesoscopic fissures during shale destruction. In this study, we have developed an integrated unit and system for monitoring sounds and pictures during propagation of mesoscopic fissures in shale to find out the deformation laws of surface, internal structure and rock body of shale during destruction, which is the theoretical foundation for further studies on wall stability of shale gas wells [29; 30; 31].