Motility is thought to contribute to the virulence of many pathogenic bacteria.In order to understand the role of motility of Vibrio harveyi in virulence, the mini-Tn10/Kan transposoninduced mutants with deficient motility in semisoft medium were constructed, screened and identified.First, a mutagenesis clone bank of V.HARVEYI TS-628 was obtained by cell conjugation between the donor E.coli Sm10 (pLOFKm) containing the mini-Tn10Kan and the recipient V.harveyi TS-628 by filter mating.And seventeen non-motile mutants were screened from the mutans bank by phenotypical characterization in semisoft medium, two of which were finally confirmed to be mini-Tn10/Kan transposon-induced motility mutants after identified by PCR and Southern blot.Then the growth rate, ability of chemotaxis and biofilm formation of the mutations and the wild type strain were assessed.