Corona virus disease 2019 (COVID-19) has become a Public Health Emergency of International Concern since its outbreak, and whether COVID-19 can transmit by aerosol remains controversial. The problem of bio-aerosol transmission in the relatively confined dental clinics has aroused wide attention in the field of dentistry. This review provided a most updated summary on the relation between bio-aerosols and dental clinics, which included the microorganisms in bio-aerosols, the bio-aerosol transmission and the sources testing methods, temporal and spatial distribution of dental bio-aerosols and summarized how to reduce the exposure to bio-aerosols in dental clinics.