Cadmium zinc lead sulfide [Cd0.8(Zn1-x,Pbx)0.2S] nano-powders were prepared by an improved coprecipitation method.The effect of Pb2+ concentration at 500 C on the phase and crystalline structure of the Cd0.8(Zn1-x,Pbx)0.2S powders were investigated by X-ray diffraction(XRD).According to the transmission electron microscopy(TEM) images,the particles size are in the range of 58 nm to 72 nm.In addition,optical band gap energy and optical constants of nano-powders were determined using the ultraviolet(UV) spectrum,Fournier transform infrared spectroscopy(FTIR),and Kramers-Kronig analysis,respectively.We calculate the refractive index n,extinction coefficient k,and dielectric function ε as a function of the wavenumber.The experiment results demonstrate that the amount of Pb+2 has been playing an increasingly important role on optical properties of CZPS nanocrystals. Cadmium zinc lead sulfide [Cd0.8 (Zn1-x, Pbx) 0.2S] nano-powders were prepared by an improved coprecipitation method. The effect of Pb2 + concentration at 500 C on the phase and crystalline structure of the Cd0.8 -x, Pbx) 0.2S powders were investigated by X-ray diffraction (XRD). According to the transmission electron microscopy (TEM) images, the particles sizes are in the range of 58 nm to 72 nm. energy and optical constants of nano-powders were determined using the ultraviolet (UV) spectrum, Fournier transform infrared spectroscopy (FTIR), and Kramers-Kronig analysis, respectively. We calculate the refractive index n, extinction coefficient k, and dielectric function ε as a function of the wavenumber.The experiment results demonstrate that the amount of Pb + 2 has been played an important important role on optical properties of CZPS nanocrystals.