In this study, the systematic stability and surface electronic properties of (100) surface GaN nanowire are investigated through first principle calculations based on density functional theory. Results suggest that Li atoms insertion on the nanowire surface can promote the NF3 adsorption. Equiproportional Li and Cs adatoms are most beneficial for the reduction of surface work function and negative electron affinity (NEA) state. The variation of work function is closely associated with the change of positive/negative charge centers and distances between charge centers, further affecting surface dipole moment. This study is expected to direct the surface activation process of Cs/Li/NF3 for NEA GaN nanowire with higher stability and longer lifetime.