The first-principle calculation method with plane-wave basis and pseudo-potentials was employed to investigate the intercalation/extraction mechanism of lithium in NiSn3Sb4. The insertion/substitution formation energies and the electronic structures of NiSn3Sb4 as well as its lithiated products were studied in order to research the migration path of lithium intercalation. The results show that lithium would firstly occupy interstitial sites, then Ni and Sn atoms are replaced gradually by additional lithium. The dissociated Ni atom can relieve the volume expansion and improve the recycling performance of the crystal. It can be also found that as lithium atoms insert into host material, intense electron transport from Li2s to Sn5p and Sb5p occurs at the Fermi level.