Abstract: Vapor heterogeneous condensation on the surfaces of PM2.5 was used to increase the removal efficiency of PM2.5 from combustion. An experimental device was set up to investigate the influence of particle initial size distribution, the amount of vapor addition, and the ratio of liquid to gas on removal efficiency. The particle size distribution and concentration at the outlet of scrubber were measured by Electrical Low Pressure Impactor (ELPI). The microstructure and major element compositions of fine particles were explored by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that the physicochemical properties of fine particles from coal and oil are very different. And it has considerable influence on heterogeneous nucleation behavior. The removal efficiency of PM2.5 of coal combustion is higher than that of oil. Both number and mass removal efficiencies increase with the increase in particle size and additional amount of vapor. The removal efficiency of 81%and 72% can be achieved for coal and oil combustion of fine particles with particle diameters of 0.4μm at 0.08kg/m3 gas, respectively. Moreover, the collection efficiency can be improved with an appropriate ratio of liquid to gas.