DEAD-box family genes encode ATP-dependent RNA helicase proteins,which are divided into VASA,PL10 and p68 sub-families by phylogenetic analysis. vasa gene was firstly discovered in fruit flies (Drosophila melanogaster) and since then its homologous genes have been cloned in various animal species. Researches revealed a specific expression of vasa gene in the germ cells. The vasa gene is essential for germ cell formation and gametogenesis. Interestingly in fruit fly,VASA protein is a component of the germ plasm, while vasa mRNA is a component of the germ plasm in zebrafish (Danio rerio). In this paper,the structure, function,expression pattern and the application of the vasa gene as a molecular marker of primordial germ cells are reviewed,and the perspective of vasa gene studies is also introduced.