Mesoporous TiO2 was synthesized by a hydrolysis-precipitation method using a renewable biological resource of nano-cellulose as the template and TiCl4 as the precursor. The photocatalytic activity of TiO2 was evaluated using the degradation of methyl orange under ultraviolet light irradiation as a model reaction. N-2 adsorption-desorption, transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetry-differential Scanning Calorimetry (TG/DSC), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used for catalyst characterization. The results show that TiO2 synthesized with acid nano-cellulose template exhibits high activity under UV irradiation. The material exhibits mesoporous structure with specific area of 192 m(2).g(-1), average pore size of 5.03 nm, and pore volume of 0.35 cm(3).g(-1). The addition of acid nano-cellulose template can reduce the amount of surface OH- of TiO2, hydroxyl groups of long-chain cellulose and surface hydroxyl groups of TiO2 bonding can inhibit the TiO2 precursor growth and aggregation, and inhibit the phase transformation from anatase to rutile.