The invention relates to a titanium dioxide/boron nitride composite material and a preparation method and application thereof. The preparation method of the titanium dioxide/boron nitride composite material comprises the following steps that boric acid, a carbon source, nitric acid and urea are mixed to be even by using water, mixed liquid is obtained, the mixed liquid is heated to be 300-500 DEGC and subjected to heat preservation for 15-30 minutes, a precursor is obtained, the precursor is subjected to heat preservation for 2-5 hours under a condition of ammonia gas and at the temperature of 700-1000 DEG C, and boron nitride is prepared; and a titanium source and boron nitride prepared in the step (1) are mixed to be even by using an alcohol solvent, then a mixture is obtained, the mixture is subjected to heat preservation for 12-24 hours at the temperature of 150-180 DEG C, and the titanium dioxide/boron nitride composite material is prepared. The prepared boron nitride has a larger specific surface area and a smaller band gap. The prepared titanium dioxide/boron nitride composite material has good adsorption and photocatalytic effects on Rhodamine B, and can rapidly and completely remove Rhodamine B dyestuff.