2-((5-mercapto-1, 3, 4 -oxadiazol-2-yl) methyl) benzo[d]isothiazol-3(2H)-one was synthesized and characterized by means of IR, 1H NMR, MS. The compound was tested preliminarily against the bacteria including Escherichia coli, Staphyloccus aurueus, Vibrio alginolyticus, Aeromonas hydrophila and Bacillus subtilis. The results show the title compound has good antimicrobial activity. Isothiazol-3(2H)-ones, 1,2-benzisothiazol-3(2H)-ones, and their heterocyclic bioisomeric derivatives are potent industrial microbiocides with antifungal and antibacterial activities[1,2], highly potent platelet aggregation inhibitor, anti-inflammatory, analgedic and anti-pyretic activities. And the biocide 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one is a nonmetallic and nonenvironmentally persistent biocide, which has been registered in several countries as an antifouling agent and has gained approval in the USA and Environmental Protection Agency. Isothiazolones represent a class of versatile intermediates in the synthesis of heterocyclic compounds . According to above facts and the principle of combination of bioactive sub-structure, we herein designed and synthesized benzisothiazolone derivatives2-((5-mercapto-1, 3, 4 -oxadiazol-2-yl) methyl) benzo[d] isothiazol -3(2H)-one, as shown in Scheme 1.