Present study was designed to evaluate the practical application of triethyl amine(TEA) injection for improving the collection efficiency of electrostatic precipitator(ESP) connected to a real operating plant. The major fuels used at the domestic power stations were bituminous coals imported from Australia, China, South Africa, and USA. Although the values of the electric resistance would be more or less different according to the type of the coals used, the unique electric resistance values of fly ash from the coals were mostly higher than $1{ imes}10^{12};{Omega}-cm$ and therefore, back corona problems were always expected to occur in the electrostatic precipitator. The particulates concentrations, smoke concentrations and their electric resistivity measured at the outlet of ESP, and the inspection of collection indicated that the injection of TEA improved the collection efficiency of particulate at collection plates of ESP. The electric resistance for, fly ash with the injection concentration of TEA 15 ppm(Purity 99.7%) was lowered to $2.1{ imes}10^{11};{Omega}-cm$ after injection from $1.9{ imes}10^{12};{Omega}-cm$ before injection. Under this condition, the dust emission content at the stack was reduced to approximately 80%, lowering the average outlet concentrations of particulates from $70;mg/Sm^3$ to $14;mg/Sm^3$.