Epidemiological studies have demonstrated that fine particulate matter (PM_2.5) exposure causes airway inflammation, which may lead to lung cancer. The activation of epithelial–mesenchymal transition (EMT) is assumed to be a crucial step in lung tumor metastasis and development. We assessed the EMT effect of low concentrations (0, 0.1, 1.0, and 5.0 μg/mL) of PM_2.5 organic extract on a human bronchial epithelial cell line (BEAS-2B). PM_2.5 samples were collected from three cities (Shanghai, Ningbo, and Nanjing) in the Yangtze River Delta (YRD) region in autumn 2014. BEAS-2B cells were exposed to the PM_2.5 extract to assess cell viability, invasion ability as well as the relative mRNA and protein expressions of EMT markers. Our findings revealed that BEAS-2B cells changed from the epithelial to mesenchymal phenotype after exposure. In all groups, PM_2.5 exposure dose-dependently decreased the expression of E-cadherin and increased the expression of Vimentin. The key transcription factors, including ZEB1 and Slug, were significantly up-regulated upon exposure. These results indicated that the PM_2.5 organic extract induced different degrees of EMT progression in BEAS-2B cells. The cell invasion ability increased in a concentration-dependent manner after 48 hr of treatment with the extract. This study offers a novel insight into the effects of PM_2.5 on EMT and the potential health risks associated with PM_2.5 in the YRD region.