The utility model discloses a covering shed suitable for processing open-air reinforcing steel bars on a construction site. Supporting column, a rotating wheel base is fixedly mounted on the outer wall of the bottom of the supporting column through a bolt; the number of the supporting columns is six to eight groups; an upper suspension rod is welded to the outer wall of the top of each set of supporting columns. The upper suspension rod is arc-shaped; a cross beam is welded to the outer wall of the top of each set of supporting columns. The two ends of the cross beam are fixedly welded to thetwo ends of the upper suspension rod, reinforcing steel bars distributed at equal intervals are fixedly connected between the cross beam and the upper suspension rod, the reinforcing steel bars form anet shape, pin holes are formed in the outer walls of one sides of every two adjacent sets of supporting columns respectively, and screw shafts are inserted into the two pin holes respectively. By the adoption of the stretching and folding technology, the utilization rate of the covering shed is increased, the cost for purchasing covering sheds of different sizes is reduced, the stability of thecovering shed body is improved, the working environment of workers is improved, and raw materials in the machining process are protected in rainy days.