The invention discloses a metal alloy electroplating liquid. The metal alloy electroplating liquid is composed of the following raw material components in parts: 30-40 parts of copper sulphate, 30-50 parts of aluminium sulphate, 50-60 parts of copper chloride, 50-60 parts of nickel hydroxide, 20-30 parts of cobalt sulphate, 30-40 parts of cobalt chloride, 10-15 parts of iron sulphate, 30-35 parts of ferrous chloride, 50-58 parts of cuprous oxide, 16-18 parts of hydrochloric acid, 15-20 parts of acetic acid, 3-4 parts of Tween-60, 4-5 parts of sodium hydroxyethyl sulfonate, 5-6 parts of allyl polyethenoxy ether, 6-7 parts of polyethylene glycol, 3-4 parts of ammonium lauryl sulphate, 5-8 parts of sodium lauryl sulphate and 200-300 parts of deionized water. The metal alloy electroplating liquid is good in stability, the surface of a plated film is high in brightness and smoothness, the flexibility of a plated layer is obviously improved, and the defects of burrs, roughness and the like on the outer surface of a plated part are basically eliminated.