A high-temperature electrostatic precipitator (ESP) is a good solution for lot gas cleaning to ensure the long-term Stability of the production system in many energy-consuming industries. The high-carbon fly ash particles in the gasification of coal pyrolysis process are typical particles with low resistivity. In this paper, the characteristics of the coal pyrolysis furnace fly ash (ash A) were compared with coal-fired power plant fly ash (ash B). The effects of their characteristics on particle removal were compared in a wire-plate ESP. The particle collection efficiency was found to decrease with increasing temperature. From 363 to 523 K, the collection efficiencies of both ash samples were as high as above 95%. However, at 623 and 723 K, the collection efficiency of ash A was obviously lower than ash B. A method of enhancing particle removal was proposed by particle conditioning to reduce the occurrence of particle re-entrainment, and the fine calcium carbonate powders were used as the conditioning particles to improve the collection efficiency. When the ratio in mass was 1:1, the particle collection efficiency of ash A increased from 93.5% to 99.2% at 623 K by particle conditioning in the ESP. The optimal effect of conditioning occurred compared with different mix proportion because the resistivity of mixing particles was 1.01 X 10(8) Omega.cm, within the scope of normal resistivity for good operation of ESP.