The surface of TiO2 particles is coated with Al2O3 film by liquid-phase precipitation method and sodium metaaluminate as coating agent. The inorganic film layer was characterized by TEM, SEM, XRF and other means, and its pigment performance was evaluated by testing the weather resistance, gloss and brightness of the coated TiO2. The alumina crystal form of the coating layer was analyzed by HRTEM combined with lattice calculation, and the effects of coating pH and temperature on the coating layer structure and pigment properties of the coating TiO2 were experimentally studied. The results show that the film layer of alumina coated with TiO2 is amorphous under acidic conditions, and the sample has better weather resistance; when pH=10, the film layer of alumina is a mixed crystal form of boehmite and bayerite, with boehmite type Mainly, the product has excellent pigment performance; when pH>11, the alumina film layer is Bayerite type, and the product pigment performance is poor. Elevated temperature increases the crystallinity of aluminum oxide in the film layer and improves the pigment properties of the TiO2 samples.