Abstract: Bioaerosol and environmental parameters were continuously collected in a large-scale dairy farm in Tianjin of China to explore the distribution of bioaerosols and the influence of multiple environmental factors on its concentration for dairy farm in typical a season. The temporal and spatial variations of concentration and particle size for bioaerosols in the dairy farm in summer were analyzed, and the importance of measured environmental factors on the concentration of bioaerosols was illustrated. Results showed that the concentration of bioaerosols at 1 m height above the ground was significantly greater than that at 4 m（P＜0.01）. As for the dispersion of carrier particle size, there was no significant difference between varied sampling points（P＞0.05）. A smaller proportion was observed at the smaller particle size of carriers. About 80% of carriers had the particle size over 2.1 μm. The importance of 10 environmental factors were analyzed on affecting the concentration of bioaerosols based on the random forest algorithm. Wind direction（WD）, temperature（T）, ultraviolet radiation intensity（UV） and suspended particulate matter concentration（PM100） showed a greater influence than other factors. The collinearity relationship among different influencing factors were analyzed through the hierarchical clustering method. There was a strong collinearity relationship among PM10, PM1 and PM2.5, and so did that between UV and GHI. This suggested that the strong collinearity influence factor can be removed to leave one factor within the group to saving the sampling cost. The conclusions obtained can provide a reference for the determination of air pollution emissions from domestic dairy farms.