Amorphous MgNi hydrogen storage alloy was synthesized by mechanically alloying (MA) with the proper milling parameters. The mechanism of amorphous formation by milling was discussed. The surface morphology and phases were analyzed by SEM and XRD. The effect of different parameters such as the mass ratio of ball to powder, the number and size of the balls, and the milling rate and time on electrochemical properties was tested. The maximum discharge capacity of the prepared amorphous MgNi alloy electrode was 450 mAh/g, but the capacity deteriorated fast