The invention provides an automatic welding system for an electrode shell of a submerged arc furnace. The automatic welding system comprises a clamping mechanism and a digital control system, whereinthe clamping mechanism is used for clamping and fixing the upper section of an electrode shell, a welding mechanism is used for welding the upper section and the lower section of the electrode shell,and the digital control system is used for controlling the welding mechanism; and the welding mechanism comprises an annular rail, a servo annular vehicle and an electric welding machine, wherein theservo annular vehicle is arranged on the annular rail and can move in the circumferential direction of the electrode shell, and the electric welding machine is installed on the servo annular vehicle.When the electric welding machine rotates around the electrode shell along with the walking of the servo annular vehicle, automatic welding is carried out on the upper section and the lower section ofthe electrode shell, manual welding of workers is not needed, the automation degree is high, the efficiency is high, the labor intensity of workers is reduced, the smelting condition is also improved, and the production efficiency is greatly improved. The digital control system comprises a control system, an annular power supply system and a variable-frequency speed reducing driving system, wherein the control system is used for controlling the walking of the servo annular vehicle and the welding of the electric welding machine, the annular power supply system is used for providing a power source for the servo annular vehicle and the electric welding machine, and the variable-frequency speed reducing driving system is used for controlling the walking speed of the servo annular vehicle.