The GaAs wafer is widely applied to semiconductor element related to telecommunication and semiconductor laser. In this research, novel fine polishing technology of GaAs wafer was investigated using TiO2-H2O2-H2O slurry system instead of NaOCl which is conventionally used as polishing slurry. And then the ultraviolet ray was applied in order to investigate the effect of TiO2 photocatalyst. The polishing characteristics were estimated by optical microscope and WYKO optical profiler. It was found that the slurry system was available for GaAs wafer polishing although the polishing rate was lower than NaOCl. Moreover, the effect of the photocatalyst of TiO2 including in slurry was investigated. In this polishing system, the effect of the photocatalyst on GaAs wafer CMP mechanism has not been confirmed yet.