Airborne bacteria especially pathogens and probiotics, have harmful/beneficial effects on the human respiratory system and skin system. The distribution of these bacteria varied with different temperature and relative humidity. The air conditioner can change indoor temperature and humidity, potentially affecting airborne bacteria. However, the current research on air conditioners paid more attention to the thermal comfort but not the bacterial risk caused by the change of the temperature and humidity In this study, two working conditions: intermittent cooling and continuous cooling of air conditioners were set up to explore the differences in the temporal and spatial distribution of culturable total bacteria, pathogen (Staphylococcus aureus) and probiotics (Lactococcus aureus). The results showed that the average concentration of total bacteria in intermittent cooling (1195±511 CFU/m3) is 2.5 times that in continuous cooling (483±199 CFU/m3); the average concentration of Staphylococcus aureus was in intermittent cooling (544±299 CFU/m3) is 4 times that in continuous cooling (136±7 CFU/m3); the average concentration of Lactococcus aureus was not different in the continuous (77±40 CFU/m3) and intermittent (73±24 CFU/m3) cooling. The concentration of total bacteria and Staphylococcus aureus fluctuated greatly in intermittent cooling. In intermittent cooling, the bacterial concentration changed significantly in different sites of the room. However, in continuous cooling, the bacterial concentration varied not obviously. On the spatial scale, the concentration of total bacteria and Staphylococcus aureus increased with the increase of the horizontal and vertical distance from the air conditioner, and decreased with the increase of the longitudinal distance from the air conditioner. In intermittent cooling mode, the risk of bacterial exposure in children"s respiratory area (z=0.5 m) is higher than that of adult"s respiratory area (z=1.5 m). The concentrations of total bacteria and Staphylococcus aureus were significantly positively correlated with temperature (p<0.001). However, there is no obvious correlation with relative humidity. In summer, using air conditioner can significantly reduce the concentration of cultivable bacteria in the room, which may benefit to our health.