Abstract: The total particulate matter (TPM) emitted from ultra-low emission coal-fired power plants contains both filterable particulate matter (FPM) and condensable particulate matter (CPM). In order to investigate the emission characteristics of CPM and the migration and variation patterns of its water-soluble ions in flue gas of ultra-low emission coal-fired power plants in China, parallel samples of CPM in five ultra-low-emission coal-fired power plants were collected at the inlet/outlet of wet flue gas desulfurization (WFGD) and the outlet of wet electrostatic precipitator (WESP) using the dilution condensation method. Their mass concentration and water-soluble ion concentration were analyzed. It was found that the mass concentration of CPM in the flue gas was significantly higher than that of FPM. The mass concentration of CPM in WFGD inlet/outlet and WESP outlet were 5.30, 4.19, and 9.13 times those of FPM, and the synergistic removal efficiencies of CPM in WFGD and WESP ranged from 8.3% to 45.3% and from 30.9% to 45.0%, respectively. Among them, \mathrmSO_4^2- was the main water-soluble ion and accounted for 42.8%, 60.5%, and 42.6% of all water-soluble ions in CPM of WFGD inlet, WFGD outlet and WESP outlet, respectively. The WFGD and WESP also had synergistic removal of water-soluble ions, with removal efficiencies ranging from 28.10% to 63.50% and 78.96%, respectively. Therefore, it was recommended to strengthen the control of CPM emissions from fixed sources in the future, and consider developing corresponding detection methods and emission standards.