The invention discloses a heating device for an energy-saving electric boiler. The heating device comprises a containing cavity and a main heating chamber. The main heating chamber is arranged at themiddle position of the containing cavity. A heating assembly is arranged at the position, corresponding to the position of the main heating chamber, of the bottom of the containing cavity. A convection channel is arranged between the containing cavity and the main heating chamber. A conveying-out pipeline is arranged at the middle position of the upper end of the main heating chamber. A flow guideassembly is arranged on the conveying-out pipeline. A conveying-in pipeline is arranged on the side face of the containing cavity. The heating device has the beneficial effects that the heating efficiency is improved, the heating speed is greatly increased, heat gathering is easier, the volume is controllable, the application range is expanded, heat losses in the containing cavity are reduced, the use safety is high, energy waste is avoided, and the energy-saving effect is achieved.