Abstract: Objective To explore the relation between indoor air quality and Legionella pneumophila aerosol concentration in public places.Methods Public buildings were chosen as study sites from Fengtai district of Beijing,Nanjing and Wuxi city of Jiangsu province,Shenzhen city of Guangdong province in 2011-2014.Temperature,humidity,wind velocity,particulate matter less than 10 μm in aerodynamic diameter (PM₁₀) and particulate matter less than 2.5 μm in aerodynamic diameter (PM_2.5) were detected.The Legionella pneumophila aerosol samples were collected in the public buildings and detected with real time PCR.Results The qualification rates of the indoor air of the public buildings were 79.4% for temperature,88.2% for humidity,75.0% for wind velocity,76.9% for PM₁₀,and 62.1% for PM_2.5,respectively.The concentration of Legionella pneumophila aerosol in the public buildings ranged from 8.75×10² to 1.79×10⁶ copies/ml,with a mean number of 2.15×10⁵ copies/ml.There were significant correlations between Legionella pneumophila aerosol concentration and temperature (P=0.002),humidity (P=0.038),PM₁₀ (P=0.002),and PM_2.5 (P=0.000) for the indoor air in the public buildings.Conclusion There is a correlation between Legionella pneumophila aerosol contamination and temperature,humidity,PM₁₀ and PM_2.5 of indoor air in public places.