Objective: To construct the cagQ gene-deleted mutant of Helicobacter pylori (H.pylori) Methods: Polymerase chain reaction (PCR) was used to amplify the homologous gene fragments (upstream and downstream of the openreading frames) of cagQ gene. The homologous gene fragments were connected to pMD18-T vector and the fragments were cut down by restriction enzyme. Then the homologous fragments were inserted into the pBluescript SK II(-) which includes kanamycin resistance gene. The suicide plasmid pBlueKM40-△cagQ was transferred into H.pylori through electroporation. The complete recombinant strain grown on agar plates supplemented with kanamycin was selected by PCR and confirmed through sequences analysis. Results: The suicide plasmid pBlueKM40-△cagQ was identified by restriction enzyme digestion and was transferred into H.pylori. The result of the genedeleted mutant was confirmed through PCR and sequencing. Conclusion: We generated the cagQ gene-deleted mutant of H.pylori(Hp26695-△cagQ).  ［Key words］Helicobacter pylori; type Ⅳ secretion system; cagQ; gene-deleted mutant