Corner connecting piece and attached lifting operation safety protection platform

The utility model relates to the technical field of building construction, in particular to a corner connecting piece capable of being matched with multi-angle construction of a corner part of a building outer wall, which comprises a first connecting piece, a second connecting piece and a connecting accessory, the end of the second connecting piece is provided with an inserting block which is inserted into the inserting hole and can swing relative to the first connecting piece along with the second connecting piece, the tail end of the inserting block is provided with an opening and a diagonal plane which is inclined towards the inner side of the second connecting piece, and the connecting accessory is embedded in an inner cavity of the inserting block in a sliding mode and can swing relative to the inserting block. The vertical section of the connecting accessory is of a triangular structure, the portion, slidably extending out of the opening of the inserting block, of the connecting accessory is used for pr