The invention discloses a flexible linear cutting method and cutting device for a dead head of a steel casting. A beaded rope saw is used for cutting the dead head of the steel casting. The method comprises the steps that according to the size of the structure of a dead head cutting face, a rope saw driving device and a beaded rope matched with the rope saw driving device in length are selected; a guiding wheel enabling the cutting direction of the rope saw and the cutting face of the dead head of the steel casting to be consistent is arranged between the dead head of the steel casting and the rope saw driving device; the beaded rope is wound on the dead head of the steeling casting, the guiding wheel, and a machine-mounted guiding wheel and a driving wheel of the rope saw driving device; the rope saw driving device goes forwards and backwards on a track consistent with the cutting direction of the beaded rope, and the cutting force of the beaded rope is adjusted and controlled well; the rope saw driving device is started to drive the beaded rope to rotate at high speed to cut the dead head of the steel casting, and cooling fluid is used for cooling in the cutting process. Beads of the beaded rope are formed through the method that alloy powder is used as a basic blank body and abrasive materials suitable for metal cutting are added, and then the materials are subjected to cold press molding and hot pressed sintering.