We constructed a H. pylori expression vector which consisted of both a His-tag and a GST tag as purification tools for recombinant protein and a chloramphenicol resistant cat gene as a reporter. The backbone of the vector pBK contained an ColEI origin of replication and a kanamycin resistant gene. A set of oligos for the His-tag and the PCR product of gst (glutathione S-transferase) gene were inserted sequentially in frame in the multi-cloning site of pBK. The orf of cat was inserted downstream of the gst to generate pBKHGC. The 3' part of H. pylori clpB and flaA were cloned into the vector which was introduced into H. pylori. Recombinant proteins were purified by GSH affinity column, digested with thrombin and were analyzed by western blotting. The final recombinant proteins were successfully purified.