The invention provides a foldable horizontal level. The key point of the foldable horizontal level is that a plurality of short cuboid horizontal levels 1 are connected together via movable connectors 2, so the foldable horizontal level can be freely folded. Horizontal levels of different lengths are used at different places, and horizontal levels with geometrical shapes are used for measurement involving multiple directions. The foldable horizontal level provided by the invention can be used at different places in the form of free combinations and is simple in structure and convenient to operate.