A magnesium alloy fluorine-free electroless nickel plating solution and nickel plating process thereof, the nickel plating solution includes an alkaline fluorine-free electroless nickel plating solution and an acidic fluorine-free electroless nickel plating solution; the pH of the alkaline fluorine-free electroless nickel plating solution Value is 10~12, and its composition is: nickel salt, sodium hypophosphite, citrate, sodium carbonate and thiourea; The pH value of described acidic fluorine-free electroless nickel plating solution is 4~6, and its composition is: nickel salt , sodium hypophosphite, citric acid and thiourea. The nickel plating process includes the following steps: polishing, degreasing and degreasing, alkali washing, pickling, activation, alkaline fluorine-free electroless nickel plating, acidic fluorine-free electroless nickel plating, and passivation. The plating solution of the present invention does not contain fluorine, is safe in composition, and does not pollute the environment. The outer layer of the composite coating obtained by nickel plating is an amorphous nickel-phosphorus alloy, and the composite coating has high compactness, good corrosion resistance, good bonding force, and good Industrial application prospects.