The behavior of nano-particles finds a wide application in opto-electronic and semi-conductor devices. ZnS nano-crystals were grown into poly-vinyl alcohol matrix by chemical route at different weight percentage. Optical properties of both un-doped and doped with ZnS nano-crystalline compounds were studied. The nano structure was characterized with the help of X-ray diffraction (XRD) and Hi-resolution Transmission Electron Microscopy (HRTEM). Surface morphology was studied with the help of Scanning Electron Microscopy (SEM). The average particle sizes of ZnS, ZnS-Ni and ZnS-Mn were found to be 6.51, 7.3 and 12 nm respectively in TEM and that obtained from Debye-Scherrer formula is about 2.3 and 2.5 nm for undoped and doped ZnS respectively. Peak of Photo-luminescence (PL) emission spectra was obtained at 375 nm at room temperature and another peak at 433 nm for Ni. Again the peak of Photo-luminescence (PL) emission spectra was obtained at 334 nm at room temperature for Mn, Mn dependant emission was found at 580 nm. These data showed successful doping. PL studies also confirmed presence of dopant in the nano crystallites. Optical absorption studies were carried out with UV-VIS Spectrophotometer and showed a strong absorbance at wavelength 400 nm with a tendency towards blue shift. Selected area electron diffraction (SAED) shows a set of four well defined rings corresponding to diffraction from different planes of the nano crystallites. HRTEM image showed a well crystalline ZnS doped with Ni and Mn. Both Raman spectra and XRD studies confirmed the well crystalline states of ZnS.