The utility model belongs to building construction field, limit safety protection warning rail is faced in construction promptly. Be particularly useful for building staristep under construction protects temporarily. Insulated column component guardrail unit between it includes at least two, every stand bottom is connected with the floor of fixing with ground, and the backplate is connected to the bottom between two stands of its characterized in that, and the railing is connected on intermediate sum upper portion, and adoption activity hinge joint spare is connected with the stand to backplate, railing. The guardrail comprises a plurality of stands and horizontal railing, so minimum guardrail unit is constituteed to two stands railing between and. Product installation, dismantlement are under construction simply, safe, reliable. Save labour, save time. Only need disposable the input, manifold cycles uses. The periphery, domatic roof periphery and the construction elevator that maintain the wall and the places such as both sides limit of building passageway are not built as yet by laying bricks or stones to balcony and staristep, each floor board of frame construction of be applicable to the foundation ditch periphery, not installing railing or sideboard as yet.