Abstract: Although conventional coal-fired pollutants have achieved ultra-low emissions, the control of unconventional pollutants such as SO₃ and condensable particulate matter has not yet been resolved. In order to achieve the synergistic control of conventional and unconventional pollutants, this work studies the synergistic removal technology of multiple pollutants in coal-fired flue gas during the condensation scrubbing process, including filterable particulate matter, SO₂, SO₃, and condensable particulate matter. A 1000 Nm³/h experimental system was built as a bypass of the tail flue of a 440 t/h circulating fluidized bed coal-fired boiler, and the flue gas was treated with humidification spray and condensation spray successively. The removal efficiency of various pollutants was tested under multiple operating conditions. The removal mechanisms and influence laws were analyzed. The optimal operating parameter range was determined. The results showed that in the process of flue gas condensation scrubbing, the removal efficiencies of filterable particulate matter, SO₃, SO₂, and condensable particulate matter were 81.9%−100%, 85.5%−93.5%, 84.8%−99.9%, and 14.8%−55.4% respectively within the operating range of liquid to gas ratio of 4.4−5.4 L/m³ and spray temperature of 18.8−28.1 ℃; The synergistic removal mechanism includes: the coagulation of fine particles and aerosol SO₃ induced by the diffusiophoresis caused by the vapor condensation on the surface of cold droplets, the absorption of SO₂, gaseous SO₃, and gaseous precursors of condensable particulate matter by low-temperature spraying droplets, and the condensation of condensable particulate matter promoted by flue gas cooling. The removal efficiencies increase with the decrease of spray temperature and the increase of liquid to gas ratio. The results suggested that condensation spray technology can effectively remove multiple pollutants, thereby being of great significance for further improving the level of coal-fired pollutant control.