Older patients are the main population suffering from lower respiratory infections, which is of high incidence and mortality. Because of the increasing age, presence of one or more co-morbidities, colonization of bacteria in the oral cavity and upper respiratory tract, and high incidence of dysphagia, all these factors increase the occurrence of aspiration pneumonia. Thus, the distribution of causative agents for lower respiratory infection in the older people is different from general population. The percentages of Gram-negative Enterobacteriaceae, Pseudomonas aeruginosa, Staphylococcus aureus and anaerobic bacteria become larger. Based on the characteristics of the elderly population, this paper focused on the features of pathogens and bacterial resistance in lower respiratory tract infection, and provided the best antibiotic treatment options according to the relative guidelines so as to provide references to the clinicians.