The invention relates to an energy-saving electric heater. The energy-saving electric heater comprises a casing, a connecting vessel is arranged in the casing, a plurality of aluminum fins are inlaid on the connecting vessel. The connecting vessel comprises horizontal channels and vertical channels which are mutually communicated, the horizontal channels and the vertical channels are filled with industrial sand or heat-conducting media containing the industrial sand, wherein heating devices are arranged in a first horizontal channel and a second horizontal channel which are positioned at the lower portion of the connecting vessel respectively, a overheat protector is arranged at the lower portion of the vertical channel which is positioned at the right end of the connecting vessel, and a turn off power protector is arranged at the lower portion of the vertical channel which is positioned at the left end of the connecting vessel. Experiments show that the energy consumption of the industrial sand and the heat-conducting media containing the industrial sand is low, and the energy consumption of the energy-saving electric heater is reduced by 60 percent compared with the energy consumption of a conventional electric heater. The industrial sand is freeze proof, insulated and high in pressure-bearing, and no pressure is generated under normal work, so that the use safety of products is guaranteed and the service life of the products is prolonged. By adopting a convection design concept and using the aluminum fins for heat conduction, heat dissipation is fast, efficient is higher, and cross-ventilation is formed through heating.