Various efforts can be made to obtain clean water in the environment by utilizing semiconductor technology. This study aims to inform the synthesis and characterization of MnO2/CuO/Fe2O3 photocatalyst for crystal violet degradation in wastewater. Nanocomposite was synthesized through a sol-gel process with three semiconductor materials doped. X-ray diffraction (XRD) was employed to analyze the nanocomposite structure and determine crystal size. Fourier Transform Infrared (FTIR) was used to provide functional groups in the nanocomposite. A Scanning Electron Microscope (SEM) can characterize surface morphology and particle size. The results of the SEM show that an increase in sintering temperature causes the smallest particle sizes to be 54.79 nm. The result of characterization using the ultraviolet-visible (Uv-Vis) spectrophotometry analysis the most effective band gap value in photocatalyst activity was 1.36 eV. The optimum percent of degradation MnO2/CuO/Fe2O3 catalyst was 50.40% for the sample at a temperature of 400o C under irradiation with sunlight for six hours. Test results show that increased sintering temperature increased the photocatalytic activity.