The invention provides a rare earth-nickel-cobalt-boron multi-element alloy anticorrosion and wear-resistant plating, an electroplating liquid and a preparation method of the electroplating liquid. The plating is of an amorphous mingled nanocrystalline structure, and the microhardness of the plating is HV700-HV1300; and the plating comprises the following components by weight percent: 1wt%-40wt% of cobalt, 0.1wt%-1.5wt% of boron and the balance of nickel and trace rare earth. The electroplating liquid comprises the following components: 180-250g/L of nickel sulfate, 20-50g/L of cobalt sulfate, 30-60g/L of nickel chloride, 2-4g/L of dimethylamine-borane, 30-50g/L of boric acid, 0.001-2g/L of rare earth, 3-5g/L of sodium tartrate, 10-30g/L of sodium citrate or citric acid, and deionzied water which is added to achieve a metered/constant volume. The preparation method of the electroplating liquid comprises the following steps: dissolving nickel sulfate, cobalt sulfate, boric acid and nickel chloride with the deionized water and regulating the pH value; and adding sodium citrate or citric acid, sodium tartrate, rare earth and dimethylamine-borane for the constant volume and sufficiently stirring. The preparation method of electroplating liquid is simple to operate, is high in current efficiency and energy-saving and environmentally-friendly; and the plating is of the amorphous mingled nanocrystalline structure, and has bright, smooth and flaw-free appearance, extremely low porosity, high hardness and good anticorrosion and wear-resistant properties and comprehensive mechanical properties.