The invention relates to a program-controlled side-moving oil cylinder circumferential seam welding machine, which consists of seven parts: an automatic control system, a power clamping mechanism, a lateral shifting device, a vertical lifting device, a welding torch swinging device, a position fine-tuning device and a welding mechanism. The invention adopts a PLC programmable controller as a main control unit, and adopts a Chinese display and video touch screen as a parameter adjustment dialogue interface. The touch screen can set the welding voltage, current welding speed and swing speed of each layer, and it is equipped with automatic and manual buttons for welding torch up and down. The invention adopts the mode of rotating the workpiece and fixing the welding torch; the welding torch is equipped with a fine-tuning mechanism and a two-axis angle adjustment device, which can adjust different welding angles; the welding torch is controlled by air pressure, and the micro DC motor drives the welding torch to swing; the tailstock is tightened by air pressure, and the machine head The three-jaw clamping method is adopted to realize automatic, manual and semi-automatic operation. The invention has the advantages of high degree of automation, good welding quality, safety and reliability.