The invention provides a circulating cooling device of a water-cooling fire grate and a waste incineration power generation device. The circulating cooling device of the water-cooling fire grate comprises a fire grate cooling water pump, an air preheater, a fire grate water heat exchanger and a distribution unit. The fire grate cooling water pump is used for pumping circulating cooling water intothe water-cooling fire grate so as to cool the water-cooling fire grate; the air preheater is used for heating air through the circulating cooling water guided from the water-cooling fire grate; the fire grate water heat exchanger is used for heating condensed water through the circulating cooling water guided from the water-cooling fire grate; and the distribution unit is used for controlling theamount of the circulating cooling water guided from the water-cooling fire grate into the air preheater and the fire grate water heat exchanger. According to the circulating cooling device of the water-cooling fire grate, distribution of heat absorbed by the circulating water can be adjusted as required, and system power consumption is reduced as much as possible on the premise that the heat is completely utilized. The waste incineration power generation device has the similar advantages.