Common bacterial blight (CBB) of common bean is one of the most serious diseases affecting the production of common bean, it can occur throughout the whole growth period of common bean. When the disease is severe, it can lead to 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 the disease, and 1 resistant material, 90 moderately resistant materials, and 189 disease-susceptible materials were identified. From the materials, we selected resistant resources of Zihuayundou and susceptible resources Talanghuacaidou for the study of immune response in the early stage of pathogen infection. The results showed that the H₂O₂ content of resistant materials was always higher than that of susceptible materials after inoculation, and the difference between resistant and susceptible materials could reach a very significant level 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 on samples of resistant and susceptible materials after inoculation. It was found that the callose content in resistant materials was significantly up-regulated 6 h after inoculation. Trypan blue staining results indicated that resistant materials could limit the spread of pathogens by controlling cell death at the inoculation site. These results showed that the resistant varieties triggered the immune response at the early stage of the pathogen infestation, and thus increased the resistance of the plants to the disease.