Li-Mg-N-H system hydrogen storage materials represented by Mg(NH2)2-2LiH has been considered to be one of the most promising solidstate hydrogen storage materials for on-board application, because it has high reversible hydrogen storage capacity and favorable thermodynamic properties. The biggest problem of this system is the high de/hydrogenation kinetic barrier. In this paper, the research progress on the components design of the Li-Mg-N-H system and their hydrogen storage properties, improvement of its hydrogen storage performance and large-scale application attempts are reviewed. The strategies for improving the hydrogen storage performance of the Li-Mg-N-H system are mainly nanosizing, catalysis and doping modification. Effective catalytic modifiers include alkali metalbased compounds (not including borohydrides), metal borohydrides, transition metals and their compounds, carbon materials, etc. Finally, the future research directions of the Li-Mg-N-H system for on-board application are discussed.