Ultrasonic thrombolysis is an effective method to treat blood clot thrombus in a blood vessel. This paper reports an OD 5 mm and an OD 10 mm piezoelectric thrombolysis transducers that vibrate longitudinally and generate a pressure field at the distal vibration tip. Studies of vibration mode, pressure field pattern, and cavitation effect were carried out. The transducers were also tested for blood clot emulsification. The results indicate both transducers are effective. The OD 10 mm transducer with a long transmission wire has shown to provide a strong cavitation effect and work effectively at low frequency, high amplitude, and high power conditions. The OD 5 mm transducer was found to operate effectively under higher frequency, low amplitude, and lower power conditions. The cavitation effect is moderate, which facilitates precision and controls over obtaining a more uniform emulsification result.