InSb as an anode material in lithium batteries has attracted considerable attention in recent investigations. An ab initio method with norm-conserving non-local pseudopotentials based on the local density functional theory has been used to investigate the non-carbon-bearing anode material InSb for lithium batteries. The formation energies of lithium intercalation and their electronic structures have been calculated. The changes of volume, band structures, electronic density of states and charge density contour plots for lithium intercalation in InSb are also discussed. We found that the formation energies of Li insertion in InSb are all about 2.2 eV per Li atom.