The invention discloses an installation device for an OPGW terminal reservation cable of a transformer substation. According to the installation device, the problems of inter-turn contact discharge and electric corrosion strand breakage caused by inter-turn induced electricity of an OPGW wound in an OPGW terminal reservation disc of an extra-high voltage, super-high voltage or high voltage transformer substation are completely solved; the safe operating rate of the OPGW terminal reservation cable of the extra-high voltage, super-high voltage or high voltage transformer substation is improved; a hidden danger of electric grid optical cable backbone line equipment is eliminated; the safe operating rate of an electric grid is increased; maintenance work at an optical cable is reduced; the operation and maintenance cost of an electrical network enterprise is greatly reduced; moreover, site construction is convenient and simple and is easy to realize. The installation device comprises a waterproof coating material, an insulating protective sleeve and thermal shrinkage treatment equipment; the tail end of the OPGW terminal reservation cable is coated with the waterproof coating material or wound with an insulating adhesive tape; the insulating protective sleeve is arranged in the part which is coated with the waterproof coating material in a sleeving manner, and is subjected to thermal shrinkage treatment through the thermal shrinkage treatment equipment, so that the air in the insulating protective sleeve is eliminated. The invention further provides a method.