Objective To investigate the breeding of acaroid mites in room air conditioners in Wuhu, China. Methods Dust was collected from the dust screens of the cabinet air conditioners and wall-mounted air conditioners used by Wuhu residents from June to October 2012. The mites breeding in the dust were classified and identified, and the mites of each species were counted. The mite breeding rates were compared by chi-square test. Results A total of 202 dust samples were collected from the dust screens of air conditioners; 3265 mites, including 2796 acaroid mites, were detected from the dust samples, and they were identified as 18 species, 14 genera, and 6 families. The mean breeding density was 10.39 mites/g of dust, and the breeding rate was 70.79%. The mite breeding rate for the cabinet air conditioners was 58.73%, versus 76.26% for the wall-mounted air conditioners (χ²=6.442, P<0.05). Pyroglyphidae, Acaridae, and Glycyphagidae were commonly seen and accounted for 53.47%, 20.96%, and 18.13% of the total tmites, respectively. Conclusion In Wuhu, acaroid mites breed heavily in the dust screens of cabinet air conditioners and wall-mounted air conditioners, with high species diversity.