The invention provides a folding box, a floating bridge, an erection method, a pile foundation loading device and a load providing method, which realize folding and unfolding, and solve the problems of large storage space and transportation difficulty of the box body in the construction. Includes an upper support assembly, a lower support assembly and a side panel assembly arranged between the upper support assembly and the lower support assembly and foldable; The floating bridge comprises a plurality of groups of folding boxes, wherein the folding boxes are inflated in the capsule, the plurality of groups of folding boxes are respectively arranged side by side along the length and width direction of the floating bridge to form a floating bridge, the two sides of the floating bridge are respectively connected with side anchors by side anchor cables, and the adjacent folding boxes are fixedly connected by fasteners; The pile foundation loading device comprises a loading detection loading detection base, a folding box and supporting columns, water injection in a bag of the folding box, one or more loading layers are arranged on the loading detection base, each loading layer comprisesa plurality of groups of folding boxes arranged side by side, and a plurality of supporting columns are arranged between an upper supporting component and a lower supporting component of each group of the folding boxes.