Abstract: This paper briefly reviews both theoretical and experimental progress in negative refraction（NR） of phononic crystals,and suggests understanding the mechanism underlying the NR by studying the scattering of waves in periodical structures on the basis of the idea of symmetry.Then,based on a finite element approach,this paper shows the phenomena of NR by adjusting parameters of a host medium.

Key words: phononic crystal, negative refraction, band structure, symmetry, finite element simulation