Trench steel cover plate assembly

The utility model discloses a trench steel cover plate assembly which comprises a corner protection piece and a cover plate on the corner protection piece. The trench steel cover plate is characterized in that the corner protection piece is a sunk type corner protection piece, and the sunk height is similar to the thickness of the cover plate; the corner protection piece is a group of angle iron which is respectively fixed on the surface of a trench or a sunk surface; the cover plate comprises two supporting seats arranged on the corner protection piece, two rib beams for connecting the supporting seats, and a top plate fixed on the supporting seats and the rib beams; the top plate is provided with a key hole; a collection box is arranged below the key hole, and a draining hole is drilled on the collection box; the collection box is movably connected with the top plate, or the bottom plate or one of the lateral plates of the collection box is detachably connected with other parts at the bottom of the collecti