The electronic and magnetic properties of ZnS nanowires doped with Cu atoms are comparatively studied in terms of the first-principles calculation. The formation energies of doped nanowires are smaller than that of the pristine one, indicating that the doing process is an exothermic reaction. The calculation shows Cu atom preferring to the surface position. The electronic structures show that ZnS doped with Cu atoms are the half-metallic ferromagnetic semiconductors and have important applications in spintronics.