Abstract: An analysis was conducted on the dust/SO₃ ratio of nearly 200 kinds of domestic coal, while a study was carried out on the effectiveness improvement and pollutant emission characteristics of a low-low temperature electrostatic precipitator (LLT-ESP) based on improved testing technologies. Results show that the dust/SO₃ ratio of most kinds of domestic coal is above 100, in which case, no risk of low temperature corrosion would occur in the application of LLT-ESPs. The LLT-ESP technology can greatly reduce the specific resistance and improve the average particle size of fly ash, increase the electric field corona and breakdown voltage, and reduce the mass flow rate and velocity of flue gas, thus greatly improving the efficiency of the ESP, with an increase in dust removal efficiency by 0.01-0.17 percentage point, a reduction in PM_2.5 emission and SO₃ emission by 48.3% and 96.6%, respectively, and with a significant increase in mass fraction of sulfur element and sulfuric acid root in fly ash.