Abstract: To determine dynamic changes of airborne microbes,concentration of different underlying surfaces in Qingdao City, monitoring points were set up in five different underlying surfaces (city streets, coastal area, drinking water source, municipal landfill site, and constructed wetlands for wastewater treatment). Airborne microbes were collected by SAS ISO100and Andersen six stage sampler. The distributions of concentration and size, diurnal variations were systematically studied. Results showed that the concentrations of airborne bacteria were decreasingly ordered:municipal landfill site＞city streets＞drinking water source＞coastal area＞constructed wetlands for wastewater treatment. The concentrations of airborne fungi were decreased as:municipal landfill site＞constructed wetlands for wastewater treatment＞drinking water source＞city streets＞coastal area. Concentrations of bacteria and fungi in the airborne were (613.1±68.9)and (1300.4±74.3)CFU/m³, which were significantly higher in landfill site than those in other underlying surfaces. Concentrations of bacteria ranged from (155.5±14.2) to (596.6±396.4)CFU/m³, while concentrations of fungi were between (401.9±78.7) to (994.7±63.4) CFU/m³in the other underlying surfaces. The concentration of airborne bacteria in coastal area was significantly higher in the afternoon than that in the morning and noon. The concentrations of airborne bacteria in the other underlying surfaces were basically the same as within experimental error.Concentration distributions of fungi were different among underlying surfaces. The concentrations of airborne fungi in city streets, drinking water source, and constructed wetlands for wastewater treatment were ordered as morning＞noon＞afternoon, while the concentration of airborne fungi in municipal landfill site showed the sequence morning＜noon＜afternoon. However, there was no statistically significant difference (P>0.05) between different times of the day except for constructed wetlands and municipal landfill site. Bacterial aerosol in five underlying surfaces were mostly distributed in stage F1(>7.0μm) with airborne bacteria showing a skewed distribution. The trend of the aerosol particle size distribution of airborne fungi was basically similar in five different underlying surfaces with airborne fungi showing normal logarithmic distribution. The maximum was in stage F4(2.1-3.3μm) except for that municipal landfill site in stage F3(3.3-4.7μm). There were differences of airborne microbes CMD (counted median diameter) among underlying surfaces. The median diameters of airborne bacteria ranged from 2.8-4.6μm. The median diameters of fungi were about 2.0μm. Slight difference existed in CMD of fungi between five different underlying surfaces.