The invention relates to a method for recycling titanium dioxide from a waste SCR catalyst. The method comprises the following steps: ultrasonically washing a waste catalyst so as to remove ash accumulated on the surface, drying, crushing, and grinding the waste catalyst into powder with a particle size more than or equal to 200 meshes; simultaneously adding the catalyst powder into a sodium hydroxide solution, and meanwhile, adding a dispersing agent so as to obtain reaction liquid, and reacting at 90-100 DEG C for 2-3 hours, carrying out solid-liquid separation and washing; and adding washedprecipitates into a hydrochloric acid solution, and stirring for reaction at the room temperature; and carrying out solid-liquid separation, washing and drying, so as to obtain titanium dioxide. By adding the dispersing agent, the agglomeration of the catalyst powder can be prevented, the contact area between the catalyst particles and an alkaline solution is furthest increased, the adequate contact between the catalyst particles and the alkaline solution is promoted, and the leaching rate of titanium and the purity of a product are remarkably increased. The method has the characteristics ofsimple in process, high in recovery rate and product purity and the like and has a very high engineering application value.