All along peoples pay extensive attention on the origin and evolution of adaptive immunity system. Agnathans, taking lamprey as the representative, are generally thought at the edge of evolving the adaptive immunity system. Therefore, it is very significantly important to further study the mechanism of adaptive immunity of agnathans for revealing the origin and evolution of adaptive immunity system. Previous studies indicated that agnathans shared some characters of adaptive immunity with higher vertebrates. In addition, a few researchers also found that some genes are homologous in the structure or function with the immunologically relevant genes of higher vertebrates. In this article, we have summarized some recent research progresses about the mechanism of adaptive immunity system of agnathans. The aim of this paper is to provide valuable clues for further studying of the origin and evolution of the adaptive immunity system of vertebrate.