Abstract: In order to determine the pathogen of walnut blight in Yunnan area and to screen the effective agent for the control of walnut blight. Using molecular biology method to identify pathogenic bacteria and Oxford Cup method to test the antibacterial activity of 8 agents against pathogenic bacteria of walnut blight,and to determine the indoor virulence of 8 agents against Xanthomonas arboricola and Pantoea agglomerans. The results showed that 3% thiamethoxone, 72% agricultural streptomycin and 16% benzoate were the most effective antimicrobial agents against both pathogens. Among them, 3% thiamethoxone and 72% agricultural streptomycin had strong bacteriostatic effect on both X. arboricola and P. agglomeras. The EC₅₀ values of this 2 antiseptic to P. agglomerans were 3.89–9.97 mg/mL, respectively, and those to X. arboricola were 4.93–14.94 mg/mL.