The chemical precipitation method was used to prepare CaCO₃/TiO₂ composite particles.Calcium carbonate was directly added to water to prepare a calcium carbonate slurry,and the previously prepared tetrabutyl titanate precursor solution was added dropwise to the calcium carbonate slurry.In the process,hydrolysis and nucleation grown to obtain CaCO₃/TiO₂ composite particles.The results shown that the surface of the CaCO₃/TiO₂ was rough,there were a large number of TiO₂ particles with a dense particle size of about 5～8nm.When the concentration of the calcium carbonate slurry was 10g/L,the tetrabutyl titanate sol was partially formed: the hydrolysis reaction [n(H₂O):n(Ti(OC₄H₉)₄)=2:1].The mass ratio of calcium carbonate to titanium dioxide was 1g:0.75g,and the reaction for 2h,the wanted composite particles were obtained.The dissolved Ca²⁺ concentration of the composite particles in the potassium hydrogen phthalate-sodium hydroxide buffer solution was the smallest,and the acid resistance was the best.