The invention relates to a metal nickel surface modification technology, in particular to a method for modifying a metal nickel surface through a molten salt Ni-Yb-plated alloy layer. The method includes the following steps that firstly, raw materials are proportioned; secondly, anhydrous CaF2-LiF basic electrolyte is purified; thirdly, molten salt electroplating is carried out; fourthly, surfacetreatment is conducted. A molten salt electrochemical method is used for directly depositing a Ni-Yb alloy plated layer on the metal nickel surface with an oxide raw material (Yb2O3 and NiO), the problems about yield, energy consumption and cost can be well solved, and the method is environmentally friendly. The Ni-Yb alloy plated layer with the thickness of 0.5-2 mm is formed on the metal nickelsurface by controlling electroplating technology parameters, so that mechanical, electric and magnetic properties and other comprehensive performance of the surface are remarkably improved.