The invention discloses a swiping electric water boiler and a work method thereof. The swiping electric water boiler comprises a waste water box, a hot water box and a cold water box connected with the hot water box. An outer linear covers the cold water box. The waste water box collects waste water through a water receiving groove and is provided with a first and a second drain pipes. A first and a second solenoid valves are arranged on the first and the second drain pipes respectively. A temperature sensor is arranged in the waste water box. A processor module collects the measuring temperature of the temperature sensor to control the first solenoid valve to open so as to drain the cold water into a sewage through the first drain pipe; or open the second solenoid valve to drain the hot water into the outer linear through the second drain pipe so as to heat the water in the cold water box. The swiping electric water boiler and the work method thereof have the advantages that by returning part of water charge, the users are encouraged to pour the waste water into the water receiving groove so as to heat the cold water box through residual temperature of the waste water.