Abstract: This paper presents a new ultrasonic radiator,which consists of a transducer,an ultrasonic horn,and a metal circular ring.The transducer and horn in longitudinal mode are used to drive a metal circular ring which vibrates in coupled vibration mode from both the radial and axial.The circular ring can effectively transform the longitudinal vibration into the radial-axial coupled vibration and generate ultrasound in the radial and axial directions of the circular ring,meanwhile,the ultrasound can be focused to form focused ultrasound field inside the circular ring.The equivalent circuit of ultrasonic circular ring radiator is deduced.Then the geometrical dimensions of the radiator are optimized,and the resonance characteristics and radiated pressure field of an ultrasonic circular ring radiator are investigated by using the finite element package ANSYS.Finally,an ultrasonic circular ring radiator has been designed and fabricated.The experimental results are in good agreement with the calculated ones.The new ultrasonic radiator has good potential to be applied in liquid processing such as sonochemistry.