Cadmium Telluride (CdTe) thin films were prepared by thermal evaporation technique in the vacuum of about 3 × 10−3 mbar .using commercial glass substrates. The CdTe thin films were the effect gamma (γ) radiation on the grain size with dose 0.5µCi and membrane surface of treated films before and after to exposure period to gamma radiation and characterized by X-ray diffraction (XRD) results showed that the films are polycrystalline structure with hexagonal lattices and had preferred growth of grains along the (002) crystallographic direction. Atomic Force microscopy (AFM) and optical microscopic recognized. The optical band gap of thin films was found to allow direct transition with energy gap of 1.7 eV.