Van der Waals heterostructures made up of different two-dimensional (2D) materials have garnered considerable attention as anodes for lithium-ion batteries (LIBs), and doping can significantly influence their electronic structures and lithium diffusion barriers. In this work, the effects of heteroatom (X = N, O, P, and S) doping in the graphene of the graphene/silicene (G/Si) heterostructure are comprehensively examined by using first-principles calculations. The stacking stability and mechanical stiffness of G/Si and doped G/Si (XG/Si) exhibit that N-doping can improve the structural stability of G/Si, thereby ensuring good cycling performance. The densities of states reveal that the dopants (N, O, and S) can greatly increase the electronic conductivity of G/Si. Importantly, the adsorption and diffusion behaviors of Li are primarily affected by the dopant and the doping site, resulting in ultrafast Li diffusivity. Therefore, N-doped G/Si at doping site 1 (S1) shows a good and balanced property, which exhibits high potential to enhance the electrical performance of G/Si materials and offers a reference for selecting dopants in other 2D anode materials for LIBs.