Composite electric heating device

The utility model relates to an electric heater, in particular to a composite electric heating device, which comprises an electric heating oven, an inlet pipe, an outlet pipe and a heat exchange pipe, the inlet pipe and the outlet pipe are mounted on the electric heating oven, the heat exchange pipe is mounted in the electric heating oven, the heat exchange pipe is a straight pipe or a spiral pipe, and the heat exchange pipe comprises an inner pipe, an outer pipe and working liquid. The inner pipe and the outer pipe are concentrically arranged, the working liquid is located between the inner pipe and the outer pipe, the two ends of the inner pipe are connected with the inlet pipe and the outlet pipe respectively, and the two ends of the outer pipe are closed; when the heat exchange pipe exchanges heat, the outer pipe transmits heat of the electric heating oven to the inner pipe through the working liquid, and the inner pipe forms an isothermal pipe and heats the working medium in the inner pipe. The heat exch