Objective To analyze the infection characteristics and epidemic trend of 9 respiratory pathogens in Shenzhen popula-tion .Methods The 5918 patients with acute respiratory tract infection were collected ,indirect immunofluorescence was used to de-tect the IgM antibody of 9 respiratory pathogens ,including legionella pneumophila type 1 (LP1) ,mycoplasma pneumoniae (MP) , rickettsia Q (COX) ,rickettsia and chlamydia pneumoniae (CPn) ,adenovirus (ADV) ,respiratory syncytial virus (RSV) ,influenza A virus (INFA) ,influenza B virus (INFB) ,parainfluenza virus (PIVs) ,the results were analyzed statistically .Results A total of 1376 samples were detected at least one pathogen in 5918 serum samples ,the total positive rate was 23 .25% .The positive rate of MP was the highest (15 .19% ) ,followed by the INFB (8 .11% ) .The positive rates of other pathogens were relatively low .The mixed infection positive rate was 4 .29% .The positive rates of MP ,INFB and PIVs in women were significantly higher than those in men(P<0 .001) .The positive rates of MP ,INFB and PIVs were different in different seasons ,the differences were statistically sig-nificant(P<0 .001) .The positive rates of MP ,ADV and INFB in 0 to 14 years old group were significantly higher than those in >14 to 60 years old group and >60 years old group(P<0 .05) .The positive rates of MP ,CPn ,ADV ,RSV ,INFB and PIVs were closely related with age in infant and children (0 to 14 years old)(P<0 .05) .Conclusion The main respiratory pathogens of SARS in Shenzhen city were MP and INFB ,the 9 pathogens had their own infection characteristics and epidemic trend .