Coal-fired power plants are known to release a large quantity of polycyclic aromatic hydrocarbons (PAHs) and particulate matter. Some power plants have been upgraded with flue gas purification equipment to achieve ultralow emission. A coal-fired unit with ultralow emission was selected to investigate the influence of gas purification equipment on the PAH distribution in flue gas. The total concentration of the 16 PAHs at the inlet of the wet flue gas desulfurization (WFGD) system was 6.340 mu g/m(3), and naphthalene (Nap) was shown to be the major PAH compound. The total concentration of the 16 PAHs at the outlet of the wet electrostatic precipitator (WESP) was 0.870 mu g/m(3), and the 5-ring and 6-ring PAHs were the major PAH compounds. The WFGD system could partially reduce the concentration of PAHs in the flue gas. The WESP eliminated most of the Nap and a portion of the gas-phase PAHs, whereas the concentrations of some 5-ring and 6-ring PAHs in the particulate phase increased as the flue gas passed through the WESP. Under ultralow-emission conditions, the total toxic equivalent value of PAHs in flue gas at the outlet of WESP was 0.293 mu g/m(3).