Deuterium ion implantation experiments into Li2TiO3 and TiO2 were performed with various ion fluences to elucidate the role of lithium on deuterium retention behavior in Li2TiO3. The experimental results showed that there were four deuterium trapping states in TiO2; two of them were interacted near the surface and the others were deuterium trapped by E'-center and bound to oxygen with forming TiO-D bond in bulk. For Li2TiO3, there were five trapping states; four of them were the same as those in TiO2 and the other was that bound to oxygen with forming LiO-D bond. The implanted deuterium was preferentially trapped by E'-center with forming hydroxide. LiOD phase was formed as increasing ion fluence. The retention of deuterium trapped by E'-center for Li2TiO3 was less than that for TiO2, indicating that the migration of lithium via irradiation defects during implantation refrains the deuterium retention in Li2TiO3.