Abstract: Piwi-interacting RNA (piRNA) is a group of small RNAs about 30 nucleotides length that isolated from mammalian reproductive cells, which could bind to the Piwi proteins and regulate its corresponding function. piRNA mainly participates in the process of development of germ cells, silence of transposon, formation of heterochromatin, DNA integrity of germ cells, and so on． It contributes to steady heredity of hereditary substance. As small interfering RNA（siRNA）, microRNA（miRNA） and piRNA is a kind of non-coding small RNAs founded in recent years. However, they are different in functions, gene distributions and characteristics. piRNA is essential for physiological modulation of spermiogenesis. The research of piRNA was further investigated, such as structural features, distribution and interactions with PIWI proteins. Furthermore, establishment of piRNA database will facilitate scientific research of piRNA.

Key words: RNA，untranslated, Germ cells, MicroRNAs, RNA，small interfering, PiRNA