This paper includes the investigation of structural, morphological, and optical properties for nanopowder CdZnS: Cu, while effect of annealing and copper doping for ternary material CdZnS have been studied. XRD analysis exhibited that the nanopowder CdZnS was cubic crystal structure with a (1 1 1) as a preferential orientation, the average of crystal size and the intensity of peaks are increasing with increasing of annealing temperature and yellow luminescence light has been observed under X-ray photons. SEM measurements showed that the samples for as-grown and annealed 200 degrees C covered with the small nanoparticle, their size ranged between 45 nm and 145 nm, and when the sample annealed up to 300 ?C these particles changed to bulks shape due to the effect of thermal energy. EDS measurements displayed that all the elements Cd, Zn, and S was composed in acceptable chemical stoichiometry ((Cd + Zn)/S = 1:1), and the ratio of Zn: Cd = 3:1, according to the amount of molarity that have been used. The bandgap of nanopowder CdZnS were determined from absorbance measurements in the visible range as 300 nm and 1100 nm, respectively, using Tauc theory, it was estimated to be equal to 3.67 eV.