Abstract： OBJECTIVE To understand the pathogen distribution of adult community-acquired pneumonia(CAP)in a comprehen-sive hospital of Beijing,so as to provide basis for clinical diagnosis and treatment and disease prevention and control.METHODS The lower respiratory tract samples of 330 adult CAP patients who were treated in the Department of Infectious Diseases of a general hospital in Beijing from 2018 to 2019 were collected,and the samples were detected by multiple real-time PCR detection methods for a variety of respiratory pathogens,and the detection of respiratory pathogens in different ages and seasons was analyzed.RE-SULTS Among the samples of 330 adult patients with CAP,respiratory pathogens were detected in 286 cases,with a detection rate of 86.67%,of which 98 cases were detected with simple bacterial infection,47 cases with Mycoplasma pneumoniae infection,16 cas-es with viral infection and 2 cases with Chlamydia pneumoniae infection.Mixed pathogens were detected in 123 samples,with a de-tection rate of 37.27%.The mixed infection of bacteria and mycoplasma pneumoniae was the most common,followed by bacterial and viral infections.The top three respiratory pathogens were Streptococcus pneumoniae,mycoplasma and Haemophilus influenzae.The detection rate of Mycoplasma pneumoniae in patients aged 18～59 is significantly higher than that in patients aged≥60 years old.CONCLUSION The main pathogens of respiratory tract infection in adult CAP patients in a general hospital in Beijing are Strep-tococcus pneumoniae,Mycoplasma pneumoniae and Haemophilus influenzae,and the mixed infection rate of CAP is high.The clini-cal also must attach importance to the mixed pathogen infection and the reasonable choice anti-infection medicine.