Abstract: Objective By monitoring the infection status of Mycoplasma pneumoniae in patients with acute respiratory tract infection during 2015-2016 in Beijing,the epidemiological characteristics for M. pneumoniae infection were analyzed. Methods A total of 13 904 respiratory samples,including throat swabs,sputum and nasopharyngeal aspiration,were collected from the acute respiratory infections cases in sentinel hospitals in all districts in Beijing from January 2015 to December 2016. Real-time fluorescence PCR was used to detect M. pneumoniae and its genotypes in samples,and χ² test was used to compare the positive detection rate of M. pneumoniae among different genotypes according to sex,age,onset time and clinical manifestations. Results A total 652 M. pneumoniae positive samples were detected in 13 904 samples,the positive detection rate was 4.69%,of which 238 (36.50%)were positive for genotype P1-Ⅰ,230 (35.28%)for genotype P1-Ⅱ,but 184 (28.22%)samples were failed in genotyping. There was no significant difference in positive detection rates between P1-Ⅰ and P1-Ⅱ(χ²=0.139,P=0.709). The positive rates of male and female patients were 4.35%(342/7 866)and 5.13%(310/6 038), respectively,with significant difference(χ²=4.726,P=0.030). The positive rate was highest in age group 6-years(10.23%, 150/1 466)and lowest in age group 60-years(1.43%,62/4 346),and the differences in positive detection rate among all age groups were significant (χ²=347.600,P=0.001). The positive rate of M. pneumoniae was 5.18% in 2016,which was significantly higher than 4.11% in 2015 (χ²=8.889,P=0.003). The positive detection rate in October-December was significantly higher than that in other months(χ²=225.000,P=0.001). The positive rate in pneumonia cases was 6.45%, significantly higher than 1.65% in cases of acute upper respiratory tract infection(χ²=166.800,P=0.001). Conclusion From 2015 to 2016,both P1-Ⅰ and P1-Ⅱ M. pneumoniae were prevalent in the acute respiratory infection cases in Beijing. Females,people aged 6-15 years were at high risk. The susceptible genotypes were different in patients in different age groups. The positive detection rate of M. pneumoniae was higher in 2016 than in 2015. M. pneumoniae infection occurred in all seasons,but peaked from October to December. M. pneumoniae infection is prone to cause pneumonia.