Abstract: CdS thin films have been prepared by high vacuum thermal evaporation on glass and silicon substrates. Doping by silver with different ratios (2 and 4%) at substrate temperature (300 K). We studying structure properties by the measurement of X-ray diffraction and the microscope of force atomic. The estimated of crystallites size from X-ray diffraction for CdS, CdS:2% Ag and CdS:4% Ag. XRD measurement disclosed that the CdS, CdS:2% Ag and CdS:4% Ag were of cubic crystal structure. Affirm the microscopy of force atomic on nano-metric size for thin films. The microscopy of force atomic realization shows the rough surface. AFM investigations showed that the produced CdS, CdS:2% Ag and CdS:4% Ag, be the shape of particles on shape of a balls. Has been determined the band gap for (CdS, CdS:2% Ag and CdS:4% Ag) from optical properties and found (2.8, 2.61 and 2.41) eV, respectively. The examine of properties solar cell (CdS, CdS:2% Ag and CdS:4% Ag) by manufacture from heterojunction (CdS/Si).