It's still a big challenge for TiO2 nanoparticles to be applied in practice due to its low quantum and limited visible light adsorption ability. Herein, we synthesized TiO2/Al2O3 nanocomposite by decorating TiO2 film on Al2O3 surface via a wet-chemical method. This nanocomposite displayed a core-shell like structure with two-phase hybrid of Al2O3 and TiO2, and possessed good adsorption and photocatalytic properties under natural indoor weak light due to synergetic effect of Al2O3 and TiO2. The maximum adsorption capacity of X-3B on TiO2/Al2O3 can attain 416.67 mg/g, and does not be influenced by solution pH until pH value is above 10.0. A reducing band gap energy (Eg = 2.94 eV) indicated Al2O3 in nanocomposite can enhance photocatalytic property by blocking the recombination of electron-hole pairs. Scavenger experiments and ESR spectra illustrated that hydroxyl radical played an important role in degradation of X-3B under natural indoor weak light. XPS analysis indicated that the excellent adsorption and photocatalytic performance were heavily related with surface hydroxyls of TiO2/Al2O3.