The invention discloses a rolling method for an O-shaped overlap joint flux-cored wire, belonging to the field of welding material processing. Four or five rolling mills are used for rolling overlap joints; the first three rolling mills roll the flux-cored wire to be U-shaped, after adding powder, rollers of the fourth rolling mill twist an axis of symmetry of the flux-cored wire for 30-90 degrees, the fifths rolling mill presses down the twisted flux-cored wire to finish the rolling of the overlap joints, or only the fourth rolling mill finishes the two working procedures of continuously twisting the axis of symmetry of the flux-cored wire and rolling the overlap joints. The rolling method is excellent in rolling stability, high in product quality and long in service life of the rollers.