Indoor air quality does a great impact on our health and there are many reasons contributing to the pollution of indoor air. At present, people have widely concerned about air conditioning system, which was regarded as potential microbial pollution sources. The study is about separation and identification of fungal microorganisms on the surface of the central air-conditioning system filters, and then researching on the colonies and mycelium grown and reproducing regular of fungal microorganisms in different thermal environment, aimed to lay groundwork of effective air microbial contamination solve by thermal methods. The result shows that the dominant fungi are Penicillium spp and Cladospo- rium spp. No matter constant or variable temperature conditions, the reproduce rate of Penicilliumspp is faster than Cladosporium spp and the relationship between colony diameter and time is liner relation. The variable temperature does obvious restrain on Penicillium spp and Cladosporium spp has the same tendency.