ZnS and metal (Mn, Cu)-doped ZnS can be successfully synthesized using hydrothermal method. Optical properties of ZnS nanoparticles were investigated and analyzed briefly at different conditions. Undoped of ZnS nanoparticles are prepared at different hydrothermal temperatures (170oC, 180oC, 185oCand 190oC). The X-ray diffraction for pure ZnS nanoparticles has shown hexagonal phase and broad peaks. The TEM microscopy of ZnS nanoparticles has been prepared at 180oC and showed spherical particle at average particles 17nm. The optical properties of ZnS nanoparticles were studied, such as absorption and energy gap for all samples at different hydrothermal temperatures. The absorption were measured at wave length (200- 900nm) for all samples .The optical energy band gap was changed at values equal to (4.16, 4.46, 4.1 and 4.35eV) with different hydrothermal temperatures at (170oC, 180oC, 185oC and 190oC) respectively. However, these values of energy gaps for ZnS nanoparticles are blue shift and larger than that bulk value due to quantum confinement. The effect of doped with (Mn, Cu) at different concentration (0.3%, 0.5%, 0.7%, and 1%) were studied. The X-ray diffraction for doping (Mn, Cu) has indicated a hexagonal phase and the grain sizes were decreasing with increasing the doping concentration. The energy gap was increased with increasing the doping concentrations for doping with (Mn, Cu).The magnetic susceptibility of ZnS nanoparticles doped with Mn, Cu are increased with increasing doping concentration. The PL spectra of ZnS a nanoparticle is around 450nm and for doping with Mn, it shows two peaks at (430nm, 618nm), while for doping with Cu it shows band center at 450nm.