The invention discloses an instant heating-type water-electricity separation heater which comprises a shell, a circulating guide system, a heating component and a control system; the circulating guidesystem consists of a plurality of electric heating tubes alternately arranged up and down, and an upper guide cavity and a lower guide cavity which are positioned on two ends of the electric heatingtubes; the lower guide cavity is connected with a water inlet pipe and a water outlet pipe; a plurality of guide holes corresponding to electric heating tubes are arranged on the upper guide cavity and the lower guide cavity; the adjacent guide holes up-and-down are communicated through a guide groove; each electric heating tube is inserted into the guide holes corresponding to two ends of the electric heating tube to form a reflow guide passage; the heating component consists of a heating film coated on the periphery of each electric heating tube, argent electrodes coated on the outside of two ends of the heating film and electrodes sleeved on the periphery of the argent electrodes; and the electrodes are connected to a power supply. The instant heating-type water-electricity separation heater changes the mode that in the prior electric water heater, an electric heating bar is directly put into water and heats the water; through combining the electric heating tubes and the heating films for heating and heat conduction, the instant heating-type water-electricity separation heater realizes real water-electricity separation and has good safety.