Abstract: Chlorine (Cl) is a harmful element and may cause technological (fouling, slagging, corrosion) and environmental issues during coal combustion. A full-scale field study of Cl emissions was conducted at six pulverized coal-fired (PC) boiler units of four coal-fired power plants in China. Flue gas samples were collected from the inlets and outlets of the existing air pollutant control devices (APCDs) to investigate their effects on speciation and distribution of Cl in the flue gas. Concurrent with flue gas sampling, coal, bottom ash, fly ash, and samples from the FGD process (desulfurization gypsum and waste water) were collected to investigate the partitioning of Cl in a full-scale combustion process equipped with APCDs. Prior to entering APCDs, Cl concentrations in flue gases in the measured power plants ranged from 93-135μg/g. Over 96.99% Cl contained in coal was released to gas phase during combustion in the examined PC boilers, and the total Cl concentration in the flue gas from boilers was in the range of 10.17-33.63mg/m³, mainly in the form of HCl. The wet FGD and de-dusting devices were able to remove the pollutants of Cl in the flue gas, wet FGD being more effective. The wet FGD process removed over 90% of Cl in the flue gas. Particulate bound Cl can be removed by de-dusting devices, and the removal efficiency of de-dusting devices varied from 12.29% to 19.86% for Cl compounds in the flue gas. The Cl released from coal combustion was transferred into slag, fly ash, desulfurization gypsum and waste water after passing through APCDs. In terms of the final Cl emissions after APCDs, Cl in slag occupied 0.35%-3.01%, and around 6.46%-15.00% of the Cl was transported into fly ash. Most of Cl was transferred into the waste water, accounting for 68.88%-77.31%, and the gypsum contained 9.19%-15.95% of the total Cl. Only 2.21%-5.54% of Cl was emitted directly into the atmosphere, and the total Cl concentration in the flue gas from stacks was in the range of 0.34-1.38mg/m³. The results indicated some possible environmental pollution of water and soil with Cl in the areas surrounding the coal-fired thermoelectric power plants in China.