The Sleeping Beauty (SB) transposon is a Tc1/mariner family transposon that has been transpositionally inactive for over 10 million years. The SB transposon system was awakened from inactive Tc1-like transposable elements by using molecular phylogenetic data in 1997. Recent studies on its transposition efficiency and mechanism have shown its broad applications in vertebrate animals for gene-screening, gene transfer, and human gene therapy. In this review, we summarize our current knowledge of Sleeping Beauty, such as structure, transposition mechanism and potential applications, and bring forward some means aiming at the limitations of transposon technology.