By using the first-principles method based on density functional theory (DFT), the CASTEP module in Materials studio was used to calculate the substitution positions of Li atom doped with Al lattice, and different substitution configurations, total energy, average atom formation energy, and charge density distributions were calculated. By calculating the total energy and the average forming energy of atoms, it is concluded that when the Li atom is doped with an Al lattice to form a replacement solid solution, it is the easiest to replace the Al atom on the surface, and the resulting replacement solid solution has the smallest binding energy and the most stable structure. By calculating the density of electron states and analyzing the Fermi energy surface, it is found that the Al-Li solid solution substituting Al atoms at the zero Fermi surface has the smallest electron state density and the most stable structure.