The influence mechanism of element substitution on the dehydrogenation ability of LiNH2 was investigated by plane wave pseudo-potential method based on density functional theory. The binding energy, density of states （DOS） and overlap population were obtained by structure calculation, the stability of LiNH2 structure and the binding nature between atoms were analyzed. Results showed that the bond strength between N and H is reduced when the Li atoms of LiNH2 are partially replaced by the Ca, Na, or Al atoms. The best effect is get by Al, Mg co-doping. The N atoms of Li（Mg）NH2 are partially replaced by the B, C, or P atoms, the effect of C is best. It is predicted that a hydrogen storage material with lower desorption temperature can be obtained by Mg, Al, C substitution to Li, N of LiNH2.