Influences of Zn vacancy defect on electronic states, magnetic and optical properties of ZnS semiconductor material are investigated by density functional theory first principle. Results show that when the concentration of Zn vacancy defect is 6.25%, ZnS semiconductor material still exhibits a direct band gap structure. Compared with the intrinsic ZnS semiconductor, the band gap is increased by 6.4%, reaching 2.19 eV. The s and p state electrons of defect system form the energy bands near Fermi energy, few in number, and Zn d electrons form the energy bands far from Fermi energy. The Zn vacancy for ZnS semiconductor is a kind of hole doping type and the hole carrier concentration can be increased by Zn vacancy. Its hole carriers within the valence bands are heavy and the electron carriers within the conduction bands are light. Zn vacant ZnS does not show magnetism. The dielectric absorption peak intensity of Zn vacant ZnS semiconductor near 210 nm decreases, the dielectric absorption peak near 170 nm disappears and a weaker dielectric absorption peak near 100 nm emerges.