Asian dust events usually transport various pollutants that considerably impact atmospheric processes, biological ecosystems, and human health in downwind areas. To date, the composition and biodiversity dynamics of airborne bacteria have rarely been investigated in urban regions during Asian sandstorms, especially in northern China. Taking Beijing as an example, this study systematically evaluated the effects of sandstorms on the diversity characteristics of airborne bacteria. Air samples were collected from the roof of buildings for nine consecutive days (April 11-19, 2015), covering a sandstorm day (April 15, 2015), as well as four days prior to and after it. After extracting DNA and performing PCR amplifying and 16S rRNA gene high-throughput sequencing, a total of 169,122 high-quality sequences were obtained. Bioinformatics analysis on these mass data showed a high richness of airborne bacteria in this city. Sandstorms could not result in increased OTU numbers, but could result in increased Pielou, Shannon, and Simpson indexes. Bacterial communities in the Beijing atmosphere consisted of 35 phyla. Among them, Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes were the dominant phyla, which accounted for 32.76%, 28.09%, 25.46% and 6.32% of the total sequences, respectively; Gemmatimonadetes (2.11%) and Acidobacteria (1.81%) followed; whereas the relative abundance of the other 29 phyla were < 1%. During the sandstorm, the relative abundance of Proteobacteria, Bacteroidetes, Gemmatimonadetes, and Acidobacteria significantly increased from 31.67%, 5.74%, 1.82%, 1.51% to 41.46%, 10.98%, 4.48%, and 4.26%, respectively; whereas Actinobacteria and Firmicutes remarkably decreased from 28.84%, 27.10% to 22.13% and 12.35%, respectively. The genera Psychrobacter, Cellulomonas, Acinetobacter, Pseudomonas, and Clostridium may be opportunistic pathogenic bacteria that potentially threaten human health. During the sandstorm, the relative abundance of these genera decreased, but their absolute abundance increased considerably. Sandstorms potentially weaken human immune capabilities, and hence the potential risks caused by these pathogenic bacteria to human health would increase during sandstorms. Hierarchical cluster and principal component analyses on bacterial communities indicated large differences between the samples from sandstorm and non-sandstorm weather conditions, whereas differences between the samples collected before and after the sandstorm were not obvious. No significant differences were detected in α and β diversity in the comparisons of the air bacterial community collected before and after the sandstorm (t test and Adonis test, P > 0.05). Thus, sandstorms could only temporarily affect the characteristics of airborne bacterial communities, but not permanently change them. Together, this study analyzed the diverse characteristics and dynamics of airborne bacterial communities in Beijing under sandstorm conditions, and the results could provide data support for environmental disaster warnings, as well as the prevention and control of airborne diseases in northern China.