The commercial nanoparticles ZnO with - P63mc hexagonal structure, particle size of hundreds of nanometer and band gap energy about of eV have been used on photocatalyst for methylene blue. The results showed that: as increasing irradiated time from 30 minutes to 120 minutes by 365 nm radiation of Narva LT 18W ultra - violet lamp, the color of methylene-blue and ZnO mixture were depleted gradually, in which the absorptance and photoluminescence intensity were also decreased.