The invention discloses a soil borrowing device for an extra-large open caisson and a using method of the soil borrowing device. The soil borrowing device comprises a main steel pipe, N hydraulic oil cylinders, N supporting rods, N scrapers and a power head, wherein the main steel pipe comprises a bottom section steel pipe and a plurality of elongated section steel pipes for splicing and elongating; a bottom end of the bottom section steel pipe is fixedly provided with an annular clamping groove; a fixing ring is fixedly arranged on an upper outer circumferential surface; the N hydraulic oil cylinders are uniformly distributed at the periphery of the bottom section steel pipe, and the upper ends of the oil cylinders are fixed with the fixing ring respectively; the upper ends of the N supporting rods are hinged with the lower ends of the hydraulic oil cylinders; two ends of each scraper are hinged with the supporting rods and the annular clamping groove respectively; and the power head is fixed with an upper extending end of the main steel pipe. When the soil borrowing device is in a non-operating state, the scrapers are tightened in a suspender shape and have small diameters, a smaller hole is needed to be formed on the top of the open caisson, and integrity of the open caisson can be improved; and when the soil borrowing device is in an operating state, the scrapers are opened in an umbrella shape, the pulping area is enlarged, and the soil borrowing efficiency is improved.