Ti3C2/TiO2 nanocomposites with high photocatalytic performance are prepared by one-step hydrothermal method. The morphology, microstructure and phase composition of the composites are analyzed and characterized by field emission scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photocatalytic properties of pure TiO2, Ti3C2 and Ti3C2/TiO2 nanocomposites are evaluated using ultraviolet-visible-near-infrared (UV-VIS-NIR, UV-3600) spectrophotometer. The photocatalytic properties of pure TiO2, Ti3C2 and Ti3C2/TiO2 nanocomposites are investigated by using a 500 W xenon lamp to simulate the degradation of organic pollutants under sunlight. Under visible light irradiation, as for Ti3C2/TiO2, the electron and hole are separated more effectively than that of pure TiO2 and Ti3C2 and thus exhibit better photocatalytic performance than TiO2 and Ti3C2. In addition, Ti3C2/TiO2 nanocomposites are heat-treated at different temperatures. The results show that Ti3C2/TiO2-350 obtained by heat treatment at 350 °C exhibits preferable photocatalytic performance and more efficient electron-hole separation behavior than pure TiO2 and Ti3C2.