The principle of a piezoelectric transducer used in this chapter is to transfer the high frequency of electrical energy to mechanical energy. Since the output displacement of piezoelectric transducer is too small, the need of amplifying the displacement of the tool is based on the design of horn shape. Since resonance frequency of the horn should be compatible with the vibration frequency of the piezoelectric vibrator. This chapter is first to conduct experiment to measure the vibration frequency and amplitude of a piezoelectric transducer (PZT) for ultrasonic vibration. According to the experimental result, the resonant frequency of the horn for amplifying the displacement of the PZT is achieved thereafter. Theoretical calculation and ANSYS simulation can be used for figuring out the geometrical shape of the piezoelectric actuated horn. In the simulation, the horn modal frequency and harmonics analysis via the ANSYS simulation reach the error less than 3 %. Experimental results will be compared and validated with the simulated results.