High levels of fine particulate (PM2.5) in indoor and outdoor air have globally threatened human health and environment. There are still few studies which concern on the emerging persistent organic pollutants like polybrominated diphenyl ethers (PBDEs) bound on PM2.5. The aim of this study was to investigate PBDEs in PM2.5 in various outdoor (metropolis, industrial, and rural areas) and indoor (library, rail station, hospital, supermarket, department store, and office) environments. PM2.5-bound PBDEs was analyzed by high resolution gas chromatography/high resolution mass spectrometry after PM2.5 was collected. Mean levels of PM2.5-bound Σ14PBDEs were 79.0 and 116 pg m–3 in outdoor and indoor air, respectively. Compared to other outdoor locations, the industrial sites, Taixi (169 pg m–3) in particular, has the highest PM2.5-bound PBDEs levels which might be attributed to nearby industrial activities and indoor to outdoor migration behaviors. For indoor air, PM2.5-bound PBDEs mean concentrations (libraries, rail stations, department stores, offices, hospitals, and supermarkets) were found to be 357, 35.3, 50.2, 73.2, 59.2, and 124 pg m–3, respectively. The high indoor PM2.5-bound PBDEs levels found in libraries are heavily affected by the presence of indoor electronic equipment or other consumer products. Similarly, this is also true for supermarkets which merchandise electronic consumer products. Although the abundant congener of deca-BDE consisted of 74.7% and 48.03% of Σ14PBDEs in the indoor and outdoor air, respectively, nona-BDEs predominantly contributed 11.6% in the indoors while tri- and tert-BDES contributed 11.3% and 16% in the outdoors. Higher brominated PBDEs are more likely due to their emission from electronic surfaces while lower brominated PBDEs are products of photochemical degradation. Other factors affecting both the indoor and outdoor air PM2.5-bound PBDE homologue levels such as migration behaviors might also be considered.