The invention provides a powder core wire and a low-temperature-resistant high-entropy alloy prepared by electric-arc deposition of the powder core. The powder core wire comprises an aluminum belt anda powder core, wherein each of the aluminum belt and the powder core consists of Co, Cr, Fe, Ni and Cu in an equal atomic ratio being 1 to 1 to 1 to 1 to 1 to 1; and the thickness of the aluminum belt is 0.5 mm. The preparation method for the wire comprises the following steps of: (1) preparing the powder core; (2) spraying a deposited powder core; (3) performing cold-rolling; and (4) performingtube coiling and wire drawing. A prepared high-entropy alloy coating has high low-temperature-resistant strength, high low-temperature hardness and high low-temperature ductility.