The invention discloses a mobile steel cylinder heating device. The mobile steel cylinder heating device comprises a base, a vertical supporting frame, an inclined supporting plate, an arc-shaped support and a control system, wherein the vertical supporting frame and the inclined supporting plate are fixed to the base; the arc-shaped support is fixed to the inclined supporting plate and used for carrying a steel cylinder; the control system comprises a controller, a temperature sensor and a heater; the temperature sensor and the heater are connected with the controller; the temperature sensor is arranged at the tail end of the arc-shaped support in the extension direction; the heater is arranged on the upper surface of the arc-shaped support; the controller receives steel cylinder temperature information collected by the temperature sensor and controls starting and stopping of the heater according to the temperature information. The mobile steel cylinder heating device is simple in structure and convenient to use. The speed of filling sulfur hexafluoride gas into equipment is high. The efficiency is high. The steel cylinder is preheated through the heater. The phenomenon of gas backflow at the beginning of gas filling of the equipment can be avoided.