In this study, the review and synthesis of ZnO and Mn-doped ZnO are discussed. ZnO is a substance that, because of its high potential in various applications such as the manufacture of solar cells, gas sensors, chemical absorbents, optical and electrical instruments, etc., is taken into consideration. ZnO and various levels of manganese (Mn) - doped ZnO were synthesized by the Sol-gel method. Characterization was carried out by XRD and SEM. Using Taguchi experimental design by software Qualitek-4. Optimum is determined, and this case was investigated by varying the time parameter. Photodegradation of Pyridine under visible light in a batch reactor by un-doped and doped ZnO. The optimal concentration of 6% Mn and calcined at 350 ° C for 3 hr was introduced. The curve map of broadened partial DOS (PDOS) and overlap DOS (OPDOS) for 6% and 10% Mn-doped ZnO have also been plotted and comprised of experimental data.