Natural rutile is one of the important raw materials for the production of TiO₂ pigment. Nowadays the high grade natural rutile resource become limiting. So it is urgent to explore a new method with low energy consumption and less environmental pollution for the preparation of synthetic rutile TiO₂. Microwave heating technology has been widely used in both research and industrial processes. Compared with the traditional heating, microwave heating is selective and the speed of it is fast. In this paper, a new method with microwave heating is proposed to the preparation of synthetic rutile TiO₂. The crystal structure and microstructure were investigated by X-ray diffraction (XRD), scanning electron microscope-energy spectrum analysis (SEM-EDAX), respectively. XRD analysis results show that the main phase of high titanium slag is anosovite, accompanied with a small amount of anatase and rutile phase. After microwave roasting, anatase has disappeared, the peak of rutile increases. SEM-EDAX analysis results show that the surface of high titanium slag is smooth. After microwave heating, some irregular rod-like particles appeared which belongs to the morphology of rutile TiO₂