Recently, super-harmonic ultrasound imaging technology has caused much attention due to its capability of distinguishing microvessels from the tissues surrounding them. However, the fabrication of a dual-frequency confocal transducer is still a challenge. In this work, 270-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> PMN-PT single crystal 1-3 composite and 28-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> PVDF thick film, acting as transmission layer and receiving layer, respectively, are integrated in a novel co-focusing structure. To realize delicate wave propagation control, microwave transmission line theory is introduced to design such structure. Two acoustic filter layers, 13-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> copper layer and 39-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> Epoxy 301 layer, are indispensable and should be added between two piezoelectric layers. Therefore, an acoustic issue can be overcome via an electrical method and the successful achievement of a dual-frequency (5 MHz/30 MHz) ultrasound transducer with a confocal distance of 8 mm can be realized. The super-harmonic ultrasound imaging experiment is conducted using this kind of device. The 3-D image of 110-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>-diameter phantom tube injected with microbubbles can be obtained. These promising results demonstrate that this novel dual-frequency (5 MHz/30 MHz) confocal ultrasound transducer is potentially usable for microvascular medical imaging application in the future.