Abstract: RNA interference （RNAi） is an ancient and highly conservative phenomenon during biological evolution. It is also one of the important mechanisms of post-transcriptional gene silencing （PTGS）- h can directionally close a gene and prevent its functions in vivo, not affecting the functions of other genes at the same time. This is propitious to study the functionds of particular genes. Therefore, RNAi has broad application prospects in gene function, gene therapy and drug development in the post-genome era.