Abstract: A foldable horizontal ruler, comprising a ruler body having at least two or more ruler units, wherein a connecting end is arranged on the ruler unit, a connecting block is arranged between the ruler units, and the connecting end forms a rotating kit with the connecting block so that the adjacent ruler units can be folded. The connecting end, arranged on the ruler unit, is provided with a connecting block, and the adjacent ruler units can be folded through the connecting block. The ruler body can be folded in multiple segments by designing more than one set of ruler body units, which makes the storage or carrying become more convenient. The magnet is arranged on the rotating shaft and the fixed pin, and the end of the ruler unit exposed. The magnet forms adsorption with the measured object, which reduces long-time lifting and reduces the user's level of fatigue.