The utility model discloses an electric water heater which can help maintain a constant temperature of outflowing water and raise a water outflow amount, and relates to the technical field of heat exchange. The electric water heater comprises a water storage tank provided with a water inlet end and a water outlet end; an external heating device disposed outside of the water storage tank and provided with a water inlet end and a water outlet end; an internal heating device disposed inside the water storage tank; an electronic thermostatic valve used for automatically maintaining the constant temperature and provided with a first water inlet end connected to the water outlet end of the water storage tank, a second water outlet end, and a water outlet end connected to the water inlet end of the external heating device; a water inlet pipe connected to the water inlet end of the water storage tank and the second water inlet end of the electronic thermostatic valve; a controller electrically connected with the external heating device and used for regulating the heating power of the external heating device; and a temperature sensor electrically connected with the controller and disposed at the water inlet end or the water outlet end of the external heating device.