Ni-W-P ternary coating was successfully deposited on AZ91D magnesium alloy by electroless plating with low energy consumption. The effect of Na 2 WO 4 concentration on the microstructure, deposition rate, corrosion behavior, adhesion force, porosity test and micro-hardness of Ni-W-P ternary coatings were evaluated. Results reveal that when the concentration of Na 2 WO 4 is 15 g/L in the plating solution, the coating with the average thickness of 17 μm is uniform and dense, and the content of phosphorus and tungsten reached 9.63 wt.% and 1.14 wt.% respectively, which presents amorphous structure. Meanwhile, when the concentration of Na 2 WO 4 is 15 g/L, the amorphous Ni-W-P ternary coating has the best corrosion resistance, among which E corr is -0.326 V, I corr is 0.003 A/cm 2 in 3.5 wt.% NaCl solution. In addition, the mechanisms of corrosion resistance for the substrate and the coating were exploded.