The quality of ultrasound imaging depends on the bandwidth (BW) and sensitivity of the ultrasound transducer (UT). In general, the BW of the UT affects the longitudinal resolution of the imaging, while the sensitivity of the UT affects the detection range of the imaging. However, the BW and sensitivity of UT have been constrained by the limitation of acoustic matching design, resulting in a mutually restrictive relationship. In this article, synergistic enhancement of BW and sensitivity properties of the Pb(Mg $_{\mathrm {1/3}}$ Nb $_{\mathrm {2/3}})\text{O}_{3}$ -PbTiO3 (PMN-PT) single crystal (SC) phased array UT was achieved with the novel acoustic reflection layer structure. The measured results of the pulse-echo response without inductance tuning demonstrate an increase in −6 dB BW of approximately 13% for the optimized UTs compared to the normal UTs. Additionally, the optimized UTs increase the echo amplitude, with a relative sensitivity (RS) of 5.8 dB higher than that of the traditional UTs. After inductance tuning, the BW and sensitivity of the optimized UT are still much better than that of the ordinary UT. Finally, the measurement results of the tissue phantom imaging show an improvement in resolution, clarity, penetration depth, and detection range for the optimized UTs. It can be concluded that the instrument composed of optimized UTs has a good application prospect in the fields of medical ultrasonic imaging and industrial nondestructive testing.