Provided is a construction safety protective fence on the lower portion of a bridge. The fence comprises a set of connected protective fences and metal baseplates, wherein one end of each metal baseplate is welded to the bottom of the corresponding protective fence, and the metal baseplates are fixedly connected to the surface of the bridge; the protective fences comprise rectangular frames (1) which are welded by square steel tubes, metal meshes (2) which are mounted on the upper portions in the rectangular frames and metal heel staying plates (3) which are on the lower portions of the rectangular frames, channel steels (8) are arranged between adjacent protective fences, and the adjacent protective fences are connected through bolts (4) which penetrate vertical rods (1a) of the rectangular frames and the channel steels; the metal baseplates comprise baseplate frames (5) and metal plates (9), wherein one end of each baseplate frame (5) is welded to the bottom of the corresponding rectangular frame, the metal plates (9) are welded to the baseplate frames, and the inner ends of the metal plates are welded to the metal heel staying plates; the bottom faces of the baseplate frames are inserted into embedded bars of a bridge protective wall and screwed by the bolts, and the adjacent baseplate frames are connected through the bolts. The construction safety protective fence on the lower portion of the bridge is flexible and convenient to disassemble and assemble, good in protective performance, and safe and reliable and can be recycled.