Explosion-proof electrical heater

The invention relates to an explosion-proof electrical heater, in particular to an explosion-proof electrical heater which can heat air in combustible gases. The electrical heater includes an electrical heated tube which is internally provided with an electric heating wire; both ends of the electric heating wire are respectively provided with an explosion-proof box; both ends of the electrical heated tube are inserted into the explosion-proof boxes hermetically; and the explosion-proof box is provided with an explosion-proof joint which is internally provided with a cable that is connected with the electric heating wire in the electrical heated tube. The explosion-proof electrical heater is characterized in that the explosion-proof box takes the shape of a cylinder and consists of a cylinder body and a cylinder cover, wherein the cylinder body is provided with through holes along the circumference of the bottom; the electrical heated tube is arranged along the circumference of the cylinder body; and both ends