A water dispenser, suited to adjust the temperature of water for drinking, comprising: a first heat-exchanger, including a first inlet, a first outlet, a second inlet, a second outlet, a first guiding-channel, and a second guiding-channel, the first inlet and the first outlet are communicated with two ends of the first guiding-channel respectively, the second inlet and the second outlet are communicated with two ends of the second guiding-channel respectively, wherein the water flows into the first heat-exchanger from the first inlet, and flows out of the first heat-exchanger from the first outlet through the first guiding-channel; a heater, one end is connected to the first outlet, another end is connected to the second inlet, the heater is suitable to heat the water flowed out of the first outlet, the heated water is suitable to flow into the first heat-exchanger from the second inlet, and flows out of the first heat-exchanger from the second outlet through second guiding-channel; a first water-storage tank and a faucet connected to an end of the first water-storage tank and the other end of the heater respectively; characterized in that the other end of the first water-storage tank is connected to the second outlet for storing the water flowed out of the second outlet; a first control valve, disposed between the heater and the faucet, wherein when the temperature of water heated by the heater is in a first predetermined temperature range, the first control valve is opened to make the water flow out of the faucet; a second control valve, disposed between the first water-storage tank and the faucet, wherein when the temperature of water in the first water-storage tank is in a second predetermined temperature range, the second control valve is opened to make the water flow out of the faucet; and a processor, controls a open state or a closed state of the first control valve and the second control valve according to a instruction input by a user. a first heat-exchanger, including a first inlet, a first outlet, a second inlet, a second outlet, a first guiding-channel, and a second guiding-channel, the first inlet and the first outlet are communicated with two ends of the first guiding-channel respectively, the second inlet and the second outlet are communicated with two ends of the second guiding-channel respectively, wherein the water flows into the first heat-exchanger from the first inlet, and flows out of the first heat-exchanger from the first outlet through the first guiding-channel; a heater, one end is connected to the first outlet, another end is connected to the second inlet, the heater is suitable to heat the water flowed out of the first outlet, the heated water is suitable to flow into the first heat-exchanger from the second inlet, and flows out of the first heat-exchanger from the second outlet through second guiding-channel; a first water-storage tank and a faucet connected to an end of the first water-storage tank and the other end of the heater respectively; characterized in that the other end of the first water-storage tank is connected to the second outlet for storing the water flowed out of the second outlet; a first control valve, disposed between the heater and the faucet, wherein when the temperature of water heated by the heater is in a first predetermined temperature range, the first control valve is opened to make the water flow out of the faucet; a second control valve, disposed between the first water-storage tank and the faucet, wherein when the temperature of water in the first water-storage tank is in a second predetermined temperature range, the second control valve is opened to make the water flow out of the faucet; and a processor, controls a open state or a closed state of the first control valve and the second control valve according to a instruction input by a user.