Common bacterial blight of common bean is one of the most serious diseases affecting the production of common bean， which occurs throughout the whole growth period of common bean， and leads to be as high as 80% yield loss. The most effective way to control the disease is to plant resistant varieties. In order to excavate disease-resistant germplasm， 280 resources of common bean were identified for resistance to common bacterial blight， and 1 resistant， 90 moderately resistant， and 189 susceptible materials were identified. We selected resistant Zihuayundou and susceptible Talanghuacaidou for the study of immune response in the early stage of pathogen infection. The results showed that H₂O₂ content of resistant material was always higher than that of susceptible material after inoculation， and the difference between resistant and susceptible materials was very significant from 12 h to 96 h. The results of DAB staining also showed that H₂O₂ accumulation existed in resistant materials at the site of pathogen inoculation. Trypan Blue staining and callose content determination were carried out for resistant and susceptible materials after inoculation. It was found that the callose content in resistant material was significantly up-regulated 6 h after inoculation. Trypan blue staining results indicated that resistant material could limit the spread of pathogens by controlling cell death at the inoculation site. These results showed that the resistant variety triggered the immune response at the early stage of the pathogen infestation， and thus increased the resistance of the plants to common bacterial blight.