Amorphous Mg–Ni–La alloys for hydrogen storage are prepared by rapid solidification. Ag nanoparticles have been deposited onto graphene sheets to form graphene/Ag (G/A) nanocomposite through solvothermal method using ethylene glycol as solvent and reducing agent. The effects of surface modification of amorphous Mg–Ni–La alloy by introduction of different contents of G/A are systematically investigated by XRD, FT-IR, SEM, TEM and conventional electrochemical tests. The results show that the discharge capacity, cycle life, discharge potential characteristics and electrochemical kinetics of the electrodes are all improved. The surface modification enhances the electrocatalytic activity of the alloy and reduces the contact resistance of the electrodes. The Mg65Ni27La8 with 20 wt.% G/A electrode has the largest discharge capacity of 814.8 mAh g−1, which is 1.33 times that of the electrode without G/A, and the best electrochemical kinetics. Further increasing of G/A content will lead to the increase of contact resistance of the electrode, resulting in the degradation of electrode performance.