The invention discloses a rotary 
air preheater dust-blocking-prevention 
synergy sealing method and 
system. The dust-blocking-prevention 
synergy sealing method includes the steps that air leaked from the heat end is guided or extracted to the cold end from the heat end, and local heat exchange elements are purged and heated. The rotary 
air preheater dust-blocking-prevention 
synergy sealing 
system comprises a heat end primary air / 
smoke side sector sealing box, a heat end primary air / secondary air side sector sealing box and a cold end secondary air / 
smoke side sector sealing box, and further comprises a heat air leakage air 
flue; the heat end primary air / 
smoke side sector sealing box and the heat end primary air / secondary air side sector sealing box are each provided with an air inlet, one end of the heat air leakage air 
flue is in 
butt joint with the air inlets, and the other end of the heat air leakage air 
flue extends to a cold end secondary air highest-temperature module. By means of the rotary 
air preheater dust-blocking-prevention synergy sealing method and 
system, H2SO4 drops and 
liquid state NH4HSO4 are gasified while the air leaked from a preheater is reduced, and the aim of removing accumulated dust is achieved; the rotary air preheater dust-blocking-prevention synergy sealing method and system have the advantages of reducing the boiler smoke discharging temperature, restraining the accumulated dust of the preheater, reducing the air 
leakage rate, prolonging the service life of the heat exchange elements and the like.