Abstract: To determine the community structure of airborne microbes in Qingdao downtown in autumn, the airborne bacteria and fungi were collected by the KC6120 air sampler and analyzed using the 16S/18S rDNA gene clone library method. Phylogenetic analysis of airborne bacteria showed that they belonged to six major phylogenetic groups: Proteobacteria (78.8%), Firmicutes (14.6%), Actinobacteria (4.0%), Planctomycetes (1.3%), Cyanobacteria (0.7%), and DeinococcusThermus(0.7%). The dominant genera of airborne bacteria included Acinetobacter (39.7%), Staphylococcus (11.3%), Sphingomonas (8.6%),  Paracoccus (6.0%) and Massilia
(5.3%). The main types of airborne fungi were Ascomycota (97.5%) and Basidiomycota (2.5%). Dominant genera of airborne fungi included Pyrenophora (76.5%), Xylaria (13.6%) and Exophiala (2.5%). The pathogens or conditioned pathogens, such as Acinetobacter, Staphylococcus, or Sphingomonas were detected in the airborne bacteria, whereas certain kinds of fungi, such as P. graminea, X. hypoxylon and Zasmidium angulare that could cause a variety of crop diseases were also detected.