Abstract: Objective To explore the epidemiology of IgM of 9 species of respiratory tract pathogens in order to guide clinical medication. Methods The serums of the hospitalized patients with respiratory tract infections caused by 9 pathogens were detected with pneumoslide IgM including Legionella pneumophila serogroup 1 (LP1), Mycoplasma pneumonia (MP), Coxiella burnetii (COX), Chlamydia pneumonia (CP), Adenovirus (ADV), Respiratory Syncytial Viruses (RSV), Influenza A (INFA), Influenza B (INFB) and Parainfluenza 1,2 and 3 (PIVs). Results Of totally 4205 serum specimens, there were 1055 positive with the positive rate of 25.09%. The MP was the dominant pathogen with the positive rate of 18.36%. There was no statistically significant difference between infection rate of male and female. The positive rates of MP and PIVs isolated from the patients aged from 60 to 135 years were lower than that of in other groups (P<0.05). The positive rate of INFB isolated from the patients aged from 0-14 years was higher than that of in other groups (P<0.05). The positive rates of LP1 in spring and winter and MP and ADV in autumn were higher than other seasons, but that of PIVs in spring was lower than other seasons (P<0.01). Conclusion MP is the most predominant pathogen causing respiratory tract infections in our hospital. It is necessary to make protection well done so as to prevent the prevalence and spread of the pathogens in peak seasons.