Abstract: Transposons, useful for random insertional mutagenesis, is able to create random DNA insertions in bacterial chromosomes for discovering new genes, and new functions of known genes. Transposon Tn917, Tn10 and mariner family transposons have been modified and used for constructing transposon insertion library and studying the functions of genes in Bacillaceae successfully. This paper describes the structures, transposition feature and the application in Bacillus spp. of the three transposons. Compared with Tn917 and Tn10, mariner family transposons transpose more randomly and independently of any host factors, making them ideal tools for random mutagenesis in bacteria.