Predicting ground conditions ahead of the tunnel face has been one of the most important requirements of tunnel construction. This study investigated the development and application of a high resolution ultrasonic wave imaging system, which captures the multiple reflections of ultrasonic waves at the interface, to detect discontinuities at laboratory scale rock mass model. Ultrasonic wave reflection imaging based on A- and B-modes was obtained through stacking, signal compensation, demodulation, and display. Experiments were carried out by using horizontal scanning and rotational scanning. Experimental studies showed that the rotational scanning method was able to identify horizontal and inclined discontinuities and the cavity on the plaster block at a fixed location. Furthermore, two discontinuities including horizontal and inclined discontinuity planes were detected. The rotating scanning technique produced images similar to those obtained by the typical horizontal scanning technique. This paper contains basic theories about the ultrasonic transducer and several experimental application results. The full-scale field application and other application will be scheduled in the future.