Abstract: This paper reviewed the development of the efficient flue gas denitrification, desulfurization and dust precipitation technology. Considering the interactions between different flue-gas purification units, it is possible to take into account the synergetic mechanism among them for a purpose of ultra-low emissions. Three practical ultra-low emission technical routes were summarized, which included the ultralow cold-side electrostatic precipitator（ESP）, wet electrostatic precipitator（WESP） and hybrid ESP/Bag particulate collector as the core technology, respectively. The existent results indicate that the synergetic allocation of various pollution control units plays an important role in achieving ultra-low emission control of coal power plants.