Abstract: By using the Koch's sedimentation method to monitor the total number of air colonies of Yellow River Conservancy Technical Institute archives indoor environment in 2011, this paper found that the air colony density in the third quarter is largest and is the minimum in the first quarter of the year.Contrasting this result with the relevant air quality standards, it found that the archives air quality could reach to the national health standards of public places air regulations (Libraries, dormitories and network center colony density is less than 30 cfu/plate, gymnasium and restaurant colony density is less than 40 cfu/plate), be in line with the Japanese air health bacteriology grade clean air standards, and be suitable for work and learning.