Washing of metatitanic acid (H2TiO3) consumes a large amount of water during the production of titanium dioxide (TiO2) by the sulfate process. In this work, ultrasound technology is used for the pretreatment of a metatitanic acid slurry before washing. The water consumptions of washing process are compared in the absence and presence of ultrasound treatment. The effects of wash liquor properties, ultrasound time, and ultrasound power on removal of iron impurities are investigated. The washed product was characterized by X-ray diffraction, scanning electron microscopy, and particle size distribution. The effects of ultrasound on the crystal structure of TiO2 and the mechanism of water saving are discussed. The results show that better removal of iron impurities from metatitanic acid is achieved using ultrasound. The saving wash liquor when using ultrasound was 93mL for washing a 100mL metatitanic acid slurry when using a pH 2 wash liquor, ultrasonic time of 30min, and 185W ultrasonic power. The average particle size was reduced from 2.11 to 1.02 mu m, which improves washing performance. The crystal lattice parameters of TiO2 exhibited no effect on rutile type or quality of product.