The invention discloses a full-automatic two-water-temperature water boiler. The full-automatic two-water-temperature water boiler comprises a heat insulation box body, a heating box, a heat exchange box, a warm boiled water storage box and a preheated water storage box, wherein the heating box, the heat exchange box, the warm boiled water storage box and the preheated water storage box are located in the heat insulation box body; an electric heater with a temperature controlled switch is arranged in the heating box; the temperature of boiled water in the heating box is lowered after heat exchange through the heat exchange box, then the boiled water enters the warm boiled water storage box, meanwhile, the temperature of cooling water in the heat exchange box is increased after heat exchange, then the cooling water enters the preheated water storage box, and when the liquid level in the heat box is lowered, the preheated water in the preheated water storage box enters the heating box. The full-automatic two-water-temperature water boiler can provide boiled water and warm boiled water with the temperature being 50-70 DEG C; and a mechanical device is adopted by the full-automatic two-water-temperature water boiler for replacing an electronic control device, thus, the reliability of the whole system is higher, the expansion coefficient of used gas or volatile solvents is high, cooling of the boiled water and preheating of cold water are achieved through the siphoning effect, electric energy and heat energy are saved, and the potential safety hazards caused by electricity usage are avoided.