The invention discloses an intercooler automatic welding method. The intercooler automatic welding method comprises the following steps that a welding work station is arranged, and comprises a welding supporting body and a supporting body rotating device; a middle rotary table is arranged and connected to the supporting body, and the middle rotary table is provided with a clamping device and a rotary table rotating device; a mechanical arm is arranged, and arranged between every two welding work stations, and the mechanical arm is provided with a welding gun achieving the welding action; a PLC control system is arranged, is connected with the mechanical arm, the clamping device and the rotating devices and controls the work states of the mechanical arm, the clamping device and the rotary device. An equipment workbench is convenient to adjust, the product covering range is wide, the welding gun of the mechanical arm is accurate and stable in running action, the welding gun has a welding joint tracking function, and welding starting, welding stopping and repairing welding can be carried out at any position. A memory function is achieved, various parameters can be adjusted on a system, and the welding parameters of multiple workpieces can be set. The advantages of being fully automatic, high in production efficiency and good in product quality consistency, saving labor cost and the like are achieved.