Abstract: 【Objective】 To study chickens with bronchial obstruction by yellow and white caseous substances. The purpose of this research is to study the bacteriological basis of bronchial obstruction. 【Methods】 The samples of bronchial blockage sites of typical dead chickens in different chicken farms were collected aseptically. The bacteriological analysis was carried out by conventional bacterial isolation method combined with 1 6S DNA sequencing, and the drug sensitivity test and pathogenicity test were carried out. 【Results】 The results showed that E. coli and E.faecalis were isolated from 18 samples collected from 11 chicken farms, among which Proteus Mirabilis was isolated from 2 chicken farms and Acinetobacter Baumannii was isolated from 1 chicken farm. Mycoplasma Galliscepticum and Mycoplasma Synoviae were not detected in all the typical chicken farms. K-B drug susceptibility test showed that Escherichia coli were resistant to Ceftaxime, Chlorampenicol, Ampicillin, Tetracycline and Compound sulfamethoxazole. Enterococcus faecali were resistant to Ceftazidime, Aztreonam and Compound sulfamethoxazole. all isolates had no pathogenicity. 【Conclusion】 This study shows that Escherichia coli, Enterococcus faecali, Acinetobacter baumannii and Proteus mirabilis can exist alone or together in the occluded Bronchi, which may be the main synergistic factor in the formation of this pathological change, while Escherichia coli and Enterococcus faecalis were found in all detected cases with strong resistance to antimicrobial drugs.