Optical cable leading-down device and indoor substation system

The utility model relates to an optical cable leading-down device and an indoor substation system. The optical cable leading-down device comprises a first retention structure, a second retention structure, a first grounding wire and a second grounding wire. One end of the first grounding wire is used for connecting an OPGW optical cable, and the other end is used for connecting a grounding grid of an indoor transformer substation at a first connection point through a first retention structure; the first end of the second grounding wire is used for connecting an OPGW optical cable, and the second end is used for connecting a grounding grid of the indoor substation at a second connection point through a second retention structure; wherein the second connecting point is arranged on a floor slab of a side wall of a power distribution device building; the first connection point and the second connection point are different in position. The grounding wire is reliably connected with the indoor transformer substation