The invention discloses a water cooling system of a multi-segment hazardous waste incinerator. The water cooling system comprises a cold water line, a front wall water cooling wall, a back wall watercooling wall, a side wall water cooling wall, a furnace top water cooling wall and a hot water line. The front wall water cooling wall, the back wall water cooling wall, the side wall water cooling wall and the furnace top water cooling wall are cooling water pipelines which are separately arranged on the front wall, the back wall, the side wall and the furnace top of the multi-segment hazardous waste incinerator; the water inlets of the front wall water cooling wall, the back wall water cooling wall, the side wall water cooling wall and the furnace top water cooling wall communicate to the cold water line; the water outlets of the front wall water cooling wall, the back wall water cooling wall, the side wall water cooling wall and the furnace top water cooling wall communicate to the hotwater line; the cold water line provides water for process and the hot water line provides water for production and domestic application. The water cooling system disclosed by the invention plays a very good role of protecting a furnace wall of the multi-segment hazardous waste incinerator, so that the weight and thickness of the furnace wall are reduced greatly. Meanwhile, the increase of the consumption of metals of the water cooling walls is less, so that the cost is low.