The invention relates to the field of incineration, in particular to a water cooling fire grate segment applied to a fire grate of an incinerator. A water cooling fire grate segment body is formed bycasting, cooling water pipes are embedded in the water cooling fire grate segment body, and the cooling water pipes are used as a water cavity in a fire grate segment; one ends of the cooling water pipes of the fire grate segment are provided with a water inlet and a water outlet, and pipe joints are welded on the ends to facilitate connection with a cooling water system; and two connecting portsat the other ends of the cooling water pipes of the fire grate segment are connected through a connecting pipe, so that cooling water can circulate in the water cavity of the fire grate segment. According to the water cooling fire grate segment applied to the fire grate of the incinerator, the surface temperature can be decreased below 250 degree centigrade, so that the service life of the fire grate segment is prolonged by more than 5 years, the maintenance period is prolonged by more than 20%, and the operating cost is greatly reduced.