The utility model provides an economic benefits and social benefits auxiliary heat exchanger system for MGGH, it is mainly met in proper order by air heater, electrostatic precipitator, draught fan, wet desulphurization tower and chimney and forms, air heater export be provided with the gas cooler that the electrostatic precipitator entry flue -gas temperature that enables to connect at the back reduces, be provided with the flue gas reheater who enables the lifting of chimney entry flue -gas temperature before the chimney, and be provided with hot media water circulation pipeline between gas cooler and the flue gas reheater to be provided with the bypass on this hot media water circulation pipeline, add economic benefits and social benefits auxiliary heat exchanger in the bypass, can is economic benefits and social benefits auxiliary heat exchanger for realize steam respectively water heat transfer and water the adverse current shell and tube type heat exchanger of water heat transfer in this adverse current shell and tube type heat exchanger, is walked tube side, heat transferring medium steam or condensate water by heat transferring medium hot media water and walks the shell side, it had both formed low temperature condition, had improved electrostatic precipitator's dust collection efficiency, can alleviate the chimney again and corrode, avoid emitting white cigarette phenomenon.