The detailed information about the migration of Li ions under an DC electric field applied along the c-axis of an α-LiI03 single crystal has been obtained by analysing the spectrum of the nuclear reaction 6Li (n, α)t in the single crystal bombarded by thermal neutrons. The migration of Li ions in the crystal can be continuously studied non-destructively by this method. The results show that the Li ions have migrated into Al-electrode when 0.1 Columb of charge is accumulated and have penetrated the Al-electrode at 0.3 Columb. The relutive density of the Li ions at various depth in the single crystal have also been measured versus different amount of accumulated charge.