The invention relates to a rotary kiln used for the production of titanium dioxide through a sulfuric acid method. A material contact surface of a burning-resistant layer is provided with a protruding cambered-surface structure at the inlet end, the protruding cambered-surface structure is used for increasing the heat transfer and mass transfer effects of an early product of titanium dioxide in the rotary kiln, accordingly, crystal form transition of early products of particles is uniformly conducted, at the same time, the particles grow more uniformly, the phenomena of overburning and insufficient burning are reduced, the quality of the early products is improved, the use amount of fuel and the air supply amount are reduced, and the powder grinding effect is improved. One end of a refractory brick is provided with a protruding block, the other end of the refractory brick is provided with a clamp groove, two adjacent refractory bricks are connected through the protruding block and the clamp groove, compared with the current fixation mode in which refractory bricks are squeezed by steel plates through striking, the fixation mode in the invention is good in fixation effect, and falling of the refractory bricks is avoided.