Denitration reaction pretreatment device system and pretreatment method

The invention provides a denitration reaction pretreatment device system and a pretreatment method. The denitration reaction pretreatment device system comprises a heat exchanger, an NOx oxidation reactor, an electrostatic dust collector, an NOx absorption reactor and a first three-way flue gas flow controller which are sequentially connected in the high-temperature flue gas circulation direction; a solid powder outlet of the electrostatic dust collector is connected with the magnetic separator; and a flue gas heat exchange port of the first three-way flue gas flow controller is connected with the heat exchanger. By adopting the device system provided by the invention, the concentration of NOx in the flue gas at the inlet of the SCR denitration system can be obviously reduced, and the load of a denitration catalyst is greatly reduced; meanwhile, by reducing the concentration of dust in the flue gas, the failure phenomenon of the catalyst caused by alkali metal poisoning, blocking, sintering, abrasion and the