The invention discloses a foldable and lightweight single-string output type strain insulator string device, comprising a transverse supporting rod and a longitudinal supporting rod, wherein the transverse supporting rod is fixed on the longitudinal supporting rod by a foldable mechanism to form a crawling ladder, the longitudinal supporting rod is composed of a plurality of longitudinal supporting rod units, a connecting point between each two longitudinal supporting rod units is the connecting point of the transverse supporting rod and the longitudinal supporting rod, a hanging hook is arranged at one end of the crawling ladder, and a fixing hook is arranged at the other end of the crawling ladder. The foldable and lightweight single-string output type strain insulator string device disclosed by the invention adopts a foldable structure, the space occupancy of the device is greatly reduced after being folded, therefore the device can be accommodated by one bag to be conveniently carried by a worker; a novel lightweight material is adopted to reduce the weight of the device, and thus the worker can directly carry the device on a tower for use; and the foldable and lightweight single-string output type strain insulator string device disclosed by the invention is convenient and quick to install, stable and reliable, and is high in safety. The transverse supporting rod is reinforced by a double-layer casing structure to guarantee working safety. The foldable and lightweight single-string output type strain insulator string device disclosed by the invention is simple and convenient to operate, and solves the problem that most people cannot output a single string of insulators.