The invention discloses a gold-copper-nickel alloy, a preparation method and applications thereof. The gold-copper-nickel alloy consists of, by weight, 15-60% of Cu, 1-5% of Ni, with the balance being Au. The preparation method comprises the following steps: in accordance with the above-mentioned weight percentage ranges, the high-purity gold, oxygen-free copper and high-purity nickel materials are weighed up; the raw materials are put in a graphite crucible in a vacuum continuous casting machine in order; the continuous casting machine is vacuumized, heated and filled with argon when all materials are melted, then the materials begin to be operated by drawing casting; the obtained wires by drawing casting have a diameter of 8mm; and the size of the finished product is achieved by further drawing operation. The gold-copper-nickel alloy in the invention is widely used as solder for an electric vacuum device, and can be used as light-load electrical contact material, winding material and slidding-ring material. Compared with the gold-copper alloy, nickel element is added in the gold-copper-nickel alloy in the invention, which avoids ordered phase transformation, enables the material to be easy to process, and raises the welding quality when the alloy used as solder.