Enlarging the capacity of Utility boiler is recognized. as 4 good way to improve the electricity generating efficiency. An increasing number of 1000 MW ultrasupercritical (USC) utility boilers are installed in China. This contribution reports the results of systematic field measurements on PM2.5 [particulate matter (PM) with aerodynamic diameters < 2.5 mu m] emitted from a 1000 MW USC utility boiler equipped with a selective catalytic reduction (SCR) denitrification (DeNO(x)) unit, two electrostatic precipitators (ESPs), and a limestone-gypsum wet flue gas desulfurization (WFGD) system. The PM samples were collected using a Dekati low pressure impactor (DLPI) and/or a Dekati gravimetric impactor (DGI) at multiple sampling sites. The results demonstrate that the particle size distributions (PSDs) of the PM at both inlet and outlet of the SCR unit exhibit a bimodal distribution, with,a fine mode at < 0.3 mu m and a coarse mode at > 0.3 mu m. Passing the PM-containing flue gas through the SCR leads to the PSDs of the fine mode particles being shifted to larger size, possibly due to the formation of ammonium sulfate and/or ammonium bisulfate as well as the reduction of flue gas temperature. The removal efficiencies of the SCR for PM1 and PM2.5 are 14.3-33.6% and 13.3-30.5%, respectively, depending on the boiler load. The ESPs substantially reduce the mass concentrations of PM1 and PK2.5 from 84.6-107 mg/Nm(3) and 417-440 mg/Nm(3) to 0.298-1.22 mg/Nm(3) and 0.812-4.41 mg/Nm(3), respectively, with overall removal efficiencies of 98.7-99.7% for PM1 and 99.0-99.8%, for PM2.5. The WFGD process leads to the disappearance of the fine mode PM and an overall removal efficiencies of up to 28.7% for PM1 and 39.6% for PM2.5. Moreover, promoting the installation of 1000 MW USC utility boilers is likely to simultaneously achieve the reduction in the PM2.5 emission besides the improvement of electricity generation efficiency, particularly when advanced dust removal devices are employed.