The invention provides an electric water heater. The electric water heater comprises a controller, an electric heating device and a water tank; the electric heating device is arranged in the water tank, and further comprises a temperature sensor, an inlet pipe valve and a water outflow pipe valve; the temperature sensor, the inlet pipe valve and the water outflow pipe valve are in communication connection with the controller; the inlet pipe valve is arranged on an inlet pipe of the water tank; the electric heating device comprises a left pipe box, a right pipe box and a floating coil pipes; the floating coil pipes are communicated with the left pipe box and the right pipe box to form closed circulation of heated fluid, and an electric heating rod is arranged in the left pipe box and the right pipe box; the left pipe box, the right pipe box and the floating coil pipes are filled with the heated fluid; one or more floating coil pipes are arranged; each floating coil pipe comprises a plurality of arc-shaped pipe bundles, center lines of the arc-shaped pipe bundles are arcs of concentric circles, and the end portions of the adjacent pipe bundles are communicated so that the end portions of the pipe bundles form the free ends of the pipe bundles; and the concentric circles are circles with the center of the left pipe box as a circle center. According to the electric water heater, by means of intelligent control of the valves, the temperature of the water tank of the water heater is controlled, energy is saved, and the intelligent degree of the water heater is improved.