In this research, red mud was naturalized by HCl and then surface modificated by oleic acid. After treatment, the pH of red mud is neutral, the contents of Al, Fe, Si, As... decreased as showed by EDX analysis. IR and TG analyses have proved that red mud surface was successfully modificated by oleic acid. SEM image of red mud prepared at 40°C and 10 percent wt. oleic acid in ethanol solvent showed the fine particles in comparison with samples prepared by other temperature and oleic acid concentrations conditions. The results of this research has explored a new application of red mud as reinforcement, filler in polymer composites.