A sintering circulating cooling waste heat cascade recovery power generation system and a process thereof belong to the sintering waste heat utilization technology field. The system comprises a sintering circulating cooling machine, a windward chamber, a leeward chamber, a heat exchanger, a fan, a waste heat boiler, a steam bag, a superheater, an evaporator, an oxygen remover, a steam turbine, a generator, a condenser, a condensate pump and a water supply pump. The totally closed system is adopted to carry out subsection cooling and cascade recovery of waste heat of sinter, thereby recovering the sensible heat of the sinter to the maximum extent; the gradual increase of the temperature of cooling air can reduce the heat exchange temperature difference with the sinter; in order to not affect the cooling effect of the sinter, the system adopts the combined mode of the sub-cycle of the cooling air and the major cycle to absorb the sensible heat of the sinter, thereby improving the waste heat recovery efficiency. Compared with the prior art, the system and the process can extremely recover the waste heat of the sinter, improve the temperature of steam which is used for power generation under the premise of not increasing the total circulating air volume, increase the waste heat power generation amount and have great economic effects.