In this thesis, magnesium silver phosphate nanoplates were synthesized in a simple and inexpensive method. To characterize this nanocomposite, X-ray diffraction, Fourier transform infrared spectroscopy, field emission electron microscopy, Zeta potential, and dynamic light scattering were used. This nanocomposite can be used for photocatalytic degradation and removing of methylene blue (cationic), acid blue 40, acid blue 29 and acid blue 92 (anionic) paint. In order to obtain the best degradation mode, all including pH, concentration, amount and composition, the percentage of photocatalyst was optimized. The energy gap of this photocatalyst was 2.4 eV. Under optimum conditions, the percentages of color removed for 60 minutes under the sunlight simulator was more than 95%. The photocatalyst was also used to degrade of methylene blue colored textile wastewater. The results indicate that the degradation reaction in the breakdown phase that causes the formation of color does not stop and also has the ability to degrade unsaturated carbon bonds. The kinetics of the degradation reaction followed all of the first-order powders used and methylene blue adsorption isotherm complied with the Harkin-Jura isotherm. In order to obtain the amount of band gap and potential of HOMO and LUMO, for magnesium phosphate and nanocomposite prepared by solid ultraviolet-visible spectroscopy and cyclic voltammetry were used.