Abstract The structural and electronic properties of Li 4 SiO 4 and Al-doped Li 4 SiO 4 have been investigated using first-principles density functional theory. The crystal structure is fully relaxed. It can be concluded that the crystalline structure has been expanded as Al doped. The calculated total energies indicate that the Al atoms may occupy the Si 1, Si 2, Si 5 and Si 6 in preference to the other Si sits. The direct band gap of Li 4 SiO 4 is 5.07 eV while Al-doped Li 4 SiO 4 has a direct band gap of 4.78 eV. The values of the band gaps indicate that both of them are insulators. The value of the band gap reduces as Al-doped, which means that the conductivity could be improved as Al-doped.