Characteristics of airborne microbes have aroused more attention in recent yearsdue to the effect of airborne microbes on health and global climate.However,the information onairborne microbes in bioaerosols over the sea is very limited.Bioaerosol samples were collectedusing a bioaerosols sampler in Spring and Autumn over the Yellow Sea and Bohai Sea.The meanconcentration of total microbes were 2.42×105 Cells/m3 and 1.22×106 Cells/m3 over the YellowSea and Bohai Sea,respectively.Concentration of total microbes was similar in Spring andAutumn over the Yellow Sea,while concentration increased significantly from Spring to Autumnover the Bohai Sea.The concentrations of the Yellow Sea was similar to that of the Bohai Sea,andconcentrations of the two seas were lower than that of Qingdao in Spring.However,concentrationover Bohai Sea was significantly higher than that in Qingdao which was higher than that over theYellow Sea in Autumn.From the coarse to the fine particle size,concentration of microbesincreased over the two seas.The size distribution over the two seas was different from the bimodaldistribution in Qingdao.Pearson correlation analysis showed that temperature had a significantnegative relationship with concentration of microbes in 1.1-2.1μm,while NOx had a significantpositively relationship with concentration of microbes in 3.3-4.7μm over the Yellow Sea.