The utility model relates to a stroke conversion device for an iron notch drilling machine for blast furnaces, which comprises an outer casing. The outer casing is provided with a first worm and a second worm inside. A tension steel wire with one end fixedly connected with the first worm is wound on the first worm. The other end of the tension steel wire penetrates through the outer casing and exposes out of the outer casing. The first worm is provided with a reset spring and is in mesh transmission with the second worm through a speed-variable gear. A shaft of the second worm extends out of the outer casing to form an output end. The stroke conversion device can be mounted in a safety area distant from the blast furnaces and can be connected with detection equipment, action stroke of an action device of the iron notch drilling machine is converted into angular displacement by the stroke conversion device, and automation and standardization of control of the iron notch drilling machine are realized beneficially.