Portal scaffolding is made of ordinary steel pipe material as a tooled standard part, which is combined at the construction site. The basic unit is made up of a pair of portal frames, two pairs of scissor braces, a horizontal beam frame and four connectors. A number of basic units are stacked vertically by means of connectors, fastened with arm buckles, to form a multi-layer frame. In the horizontal direction, reinforcement bars and horizontal beam frames are used to make the adjacent units integral, together with inclined ladders, balustrade posts and crossbars to form an external scaffold with upper and lower step connections.