To increase desulfurization efficiency of oxidizing roasting in muffle furnace, microwave is used to roast the high-sulfur bauxite. The influences of roasting temperature and time on sulfur content are investigated, and the final phases are recognized by XRD analysis. The results show sulfur content is less than 0.7% after being roasted at 400 ℃ for 2 min. If it’s roasted at higher temperature for longer time, like 550 ℃ for 10 min, the sulfur content decreases to 0.23%. Sulfide ion can be dissociated by microwave and diffuses to the surface to form sulfur dioxide. This process will accelerate dissociation further so as to increase desulfurization efficiency.