Titanium dioxide with different ratios of anatase to brookite has been prepared by a facile hydrothermal method in the presence of tartaric acid. The resulting samples were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, UV-Vis diffuse reflectance spectra, and Brunauer-Emmett-Teller analysis. The contents of anatase and brookite in the TiO2 particles have been successfully controlled by simply adjusting molar ratio of tartaric acid to Ti in reaction system. The degradation of Rhodamine B in aqueous solutions reveals that the catalyst containing 78.7 % anatase and 21.3 % brookite has the highest photocatalytic activity. A proposed mechanism is discussed to interpret the evolution of the phases based on the effect of different C4H6O6/Ti molar ratios.