Construction elevator downwards installed and installing platform of construction elevator

The invention provides a construction elevator downwards installed and an installing platform of the construction elevator. The construction elevator comprises an installing frame, a hanging rod, standard joints, a cage, wall attaching frames and an installing platform. The construction elevator is characterized in that the installing frame is fixed to the ground, the first standard joint is fixed to the installing frame, every standard joint installed later is closely arranged below the previous standard joint, and the corresponding wall attaching frame is arranged between the standard joint and a pit every time after the multiple standard joints are installed. The cage is arranged on the side faces of the standard joints and can move up and down along the standard joints, the hanging rod is arranged on the top of the cage, the installing platform is arranged on the cage and can rotate relative to the cage, the installing platform is used for temporally storing and transferring the standard joints, and the f