Objective To analyze the characteristics of aspiration pneumonia caused by aspiration secondary bacterial infection, the characteristics of pathogenic bacteria and the treatment plan, so as to provide basis for clinical diagnosis and treatment of aspiration pneumonia. Methods The clinical data of 53 patients who were diagnosed with aspiration pneumonia in the emergency department of Beijing Tsinghua Changgeng Hospital from November 2019 to July 2020 were selected. According to the results of etiology, the patients were divided into 44 cases of Gram negative (G-) bacteria group and 9 cases of Gram positive (G⁺) bacteria group. Collect patient demographic data, laboratory indicators, pathogen detection results, antibiotic use and effectiveness and other data. SPSS statistics 25.0 was used for data analysis. According to data type, t-test, rank sum test, Fisher exact probability method or Chi-square test was applied. Results The average age of patients in this study was (79.94±1.86) years. 77.4% (41/53) of the patients had neurological dysfunction, and the main clinical manifestations were fever, dyspnea, disturbance of consciousness and cough, accounting for 37.7% (20/53), 28.3% (15/53), 20.78% (11/53) and 13.2% (7/53) respectively. There was a statistically significant difference between the two groups in terms of neurological dysfunction and disease severity (P<0.05). The strains in the G-group were mainly Klebsiella pneumoniae [52.3% (23/44)], Pseudomonas aeruginosa [29.5% (13/44)] and Escherichia coli [18.2% (8/44)], while the strains in the G⁺group were mainly Corynebacterium striatum [22.2% (2/9)] and Staphylococcus aureus [77.8% (7/9)]. The severe group was mainly infected by Klebsiella pneumoniae [51.3%(20/39)]; χ² =9.102, P=0.036]. In terms of efficacy evaluation, the initial effective rate of cefoperazone sulbactam, an antibiotic including β-lactamase inhibitor, was the highest [90.0% (18/20); χ²=14.95,P=0.011]. Conclusion Inhalation pneumonia is more common in elderly patients, especially those with nervous system dysfunction. G-bacteria are the main pathogens, and Klebsiella pneumoniae is the most common. Antibiotic treatment is an effective treatment plan, and antibiotics including β-lactamase inhibitor can be used as a first-line choice for anti-infection treatment.