In this work, ferric stearate, ferrocene and nickel N,N-dibuty dithiocarbamate (NiDBC) were utilized as photocatalyst for the decolorization of methylene blue (MB) aqueous solutions under sunlight irradiation. Pure MB solution was used as reference. Absorption intensities and surface morphology of these photocatalyst were investigated by Diffuse Reflectance Spectroscopy (DRS) and Scanning Electron Microscopy (SEM).The study indicated that ferric stearate had minimal promotion to the decolorization of MB aqueous solutions; and ferrocene exhibited better photocatalysis ability after had been irradiated 60 hours. In this study, NiDBC showed the best photocatalysis ability from the beginning. Furthermore, NiDBC enhanced the decolorization of MB after been irradiated for 31 hours. And after being irradiated 270 hours, the MB aqueous was completely decolorized by NiDBC.