Abstract: ObjectivesTo construct EHEC O157:H7 DNA bank forth screening of patho genicity island LEE.MethodsChromosomal DNA of Enterohaemorrhagic E.Coli O157:H7 was extracted and digested with Xmal.Then it was ligated to pJB8X and packed with Kphages.The products of package were used to infect E.coli DH5α and the capacity of DNA bank was identified.ResultsThe content of the bank was about 700 clones,which was larger than that of the theo retical value.ConclusionThe bank has been constructed successfully for screening any fragment you want.