Extending device and method of optical fiber mother material

The invention relates to extending device and method of an optical fiber mother material. A mother material ingot is extended into a mother material bar with smaller diameter, and the flexibility of the extended optical fiber mother material bar is reduced. The extending device comprises an extension delivering mechanism part, an extension heating furnace, an extension leading and taking mechanism part and a measurement control part, wherein the extension delivering mechanism part is installed on the extension heating furnace, the extension leading and taking mechanism part is installed under the extension heating furnace, and the measurement control part is installed at the lower part of the extension heating furnace; the extension delivering mechanism part comprises a servo motor I, a drive screw rod I, a screw rod nut I, an X-Y control unit I and a suspending chuck; the extension heating furnace is heated in an induction heating or resistance heating way; the extension leading and taking mechanism part comprises a servo motor II, a drive screw rod II, a screw rod nut II, an X-Y control unit II and a chuck for stretching; the measurement control part comprises an outer diameter measurer, a position measurer, a flexibility measurer and a programmable logic controller (PLC).