The invention discloses a system and a method for using sintering waste heat to generate electricity and belongs to the technical field of sintering waste heat electricity generation of the steel works. The system comprises a sintering machine, a hot gas outlet pipe, a gas waste heat boiler, a main exhaust fan, a ring cooling machine, a first and second stage heat waste gas collecting pipe, a waste gas heat boiler, a draught fan, a circulating fan, a chimney, a low pressure steam drum, a middle pressure steam drum, a feed pump, a pressure reducing valve, a collecting header, a steam turbine, a generator, a condenser and a condensate pump. The invention realizes utilizing the waste heat of the non-desulfurization flue header of the sintering machine without arranging an inducing fan by reasonably designing the hot gas connecting mode of the air box at the tail part of the sintering machine and the gas resistance of the waste gas heat boiler. First and second stage sealing covers of thering cooling machine are uniformly provided with a plurality of waste gas branch pipes so as to realize uniform distribution of the waste gas pressure in the sealing covers and reduce air leakage. Part of waste gas is adopted to circulate to improve the temperature of the waste gas. Compared with the existing system for using sintering waste heat to generate electricity, the system of the invention sufficiently uses the waste heat of the sintering system, improves the waste heat generated energy and reduces the operation cost.