The invention discloses a method and a system for realizing reduction of heavy metal and NOx pollutant emission of a power station boiler and belongs to the technical field of smoke pollutant control. In the system, raw coal is conveyed to a pyrolyzing furnace and a coal mill through a belt; a top outlet of the pyrolyzing furnace is connected with a boiler burner; a bottom outlet of the pyrolyzing furnace is connected with an activating oven; the activating oven is connected with a modifying machine; the modifying machine is connected with a boiler flue through a pipeline and an injection system. According to the method, part of the fuel coal in the boiler is pyrolyzed by the pyrolyzing furnace and the generated pyrolyzed gas is conveyed to a boiler re-burning burner and then is burned, so that the NOx emission in the boiler is reduced; the bottom coke of the pyrolyzing furnace is conveyed into the activating oven through a discharging system and then is activated at high temperature; the activated active coke is modified by the modifying machine and then is conveyed to an ejection pipeline through a pneumatic conveying pipeline; the modified active coke is injected into the boiler flue through the ejection pipeline; the heavy metal pollutants in the smoke are absorbed and removed by the active coke in the flue. According to the method provided by the invention, the heavy metal and NOx pollutant emission of the boiler is effectively reduced.