The invention discloses a heating device. The heating device comprises an electric heating plate, wherein the electric heating plate is square, rhombic or elliptical or is in other irregular shapes; a groove is formed in the middle of the electric heating plate; an electric heating wire is arranged in the groove, is connected with a lead and is used for being connected with a power supply for heating; a plurality of radiating fins integrated with the electric heating plate are arranged on the plate surface, far away from the groove, of the electric heating plate; a gap is formed between every two radiating fins, and each gap is vertically through. When the heating device provided by the invention is applied to a terminal box, heat emitted by the electric heating plate is quickly dissipated, the dehumidification and heat preservation efficiency is improved, the working environment of a temperature and humidity controller in the terminal box is greatly improved, the service life of the temperature and humidity controller is effectively prolonged, and the safe and stable operation of a power grid is guaranteed.