The diatomite-based porous ceramics was made by low-temperature sintering. Then the nano-TiO2/diatomite-based porous ceramics composite materials were prepared by hydrolysis deposition method with titanium tetrachloride as the precursor ofTiO2and diatomite-based porous as the supporting body of the nano-TiO2. The structure and microscopic appearance of nano-TiO2/diatomite-based porous ceramics composite materials was characterized by XRD and SEM. The photocatalytic property of the composite was investigated by the degradation of malachite green. Results showed that, after calcination at550°C,TiO2thin film loaded on the diatomite-based porous ceramics is anataseTiO2and average grain size ofTiO2is about 10 nm. The degradation ratio of the composite for 5 mg/L malachite green solution reached 86.2% after irradiation for 6 h under ultraviolet.