The invention discloses an integrated modification method for reducing pollutant emission of a circulating fluidized bed boiler. The modification method comprises the following steps: modifications on a screen type heating surface, a material return system, an air distribution system, a secondary air nozzle system, a slag cooling system and a desulfurizer adding system. Through the modifications, the concentration of SO2 and NOx in smoke is finally reduced to 30-70% of that before modifications, the fly ash concentration is reduced to 70-90% of that before modifications and the environmental protection characteristic of boiler operation can be remarkably improved without adding new equipment. The integrated modification method has the advantages of being small in investment cost, short in modification period and stable in boiler operation; at the time the integrated modification is performed, the problems existing in arrangement of the original heat surface, a funnel cap, a separator, a slag cooler and a lime stone transmission system of the boiler can be synchronously solved, and therefore the economy, stability and safety performance of boiler operation are comprehensively improved.