As an emerging non-invasive surgical technique,high intensity focused ultrasound (HIFU) has been used clinically in the treatment of various benign and malignant sol id tumors.The focusing efficiency of HIFU transducer still need to be improved to achieve safer and more effective tumor treatment.This paper reviews the principle of the extraordinary acoustic transmission,as well as the recent research on HIFU transducers that utilizing extraordinary acoustic transmission.Two aspects of work are involved:(1) The artificially acoustic structure is introduced into the design of concave acoustic lens,and a corrugated lens is designed and manufactured to improve the acoustic lens of the lens-focused transducer,which has achieved the effect of reducing side lobe and improved the safety of HIFU treatment;(2) Based on spherically periodic slot array,a metamaterial focusing transducer is designed and manufactured to enhance the focusing efficiency of the HIFU transducer.Enhanced acoustic focusing is demonstrated by both measuring and simulating sound pressure distribution of metamaterial focusing transducer and traditional concave transducer,as well as temperature elevation generated in the tissue.The results of this paper can further promote the wide application of HIFU in clinical treatment.