Peptide nucleic acid(PNA) is a kind of artificial DNA mimic. PNA hybridizes with DNA or RNA by means of Watson-Crick's base-pairs complementary with high stability, affinity and selectivity. PNA not only regulates. DNA replication, but also adjusts DNA transcription (or reverse transcription) and translation. Many applications have been explored as a new kind of molecular biological tool and a gene-targeting strategy.