The invention discloses an acoustic device and a preparation method. The acoustic device comprises an ultrasonic probe, a coupling layer, an energy collector, an adhesive layer and a wave guide rod. The diameter of the ultrasonic probe is more than 10mm. The diameter of the wave guide rod is less than 1mm. The coupling layer is used for coupling the first end surface of the ultrasonic probe and the large end surface of the energy collector. The energy collector is a taper sleeve-shaped energy collector and comprises a large end surface and a small end surface. An axial through hole is formed in the energy collector. The acoustic end of the wave guide rod is located in the through hole in the energy collector and is connected with the surface of the through hole in the energy collector through the adhesive layer in an adhesive mode. The end face of the acoustic end of the wave guide rod is flush with the large end surface of the energy collector and is coupled with the first end surfaceof the ultrasonic probe through the coupling layer. The heated end of the wave guide rod is positioned outside the energy collector. The acoustic device is used in the thermal ultrasonic fields of ultrasonic temperature measurement, ultrasonic melting point measurement, ultrasonic thermal therapy and the like. The device can greatly improve the acoustic energy transmission efficiency, and is goodin acoustic consistency, simple in structure, easy to assemble and operate and convenient to use.