The invention relates to methods for preparing and applying a titanium dioxide-carbon composite photocatalyst. The technical scheme is that the method for preparing the titanium dioxide-carbon composite photocatalyst comprises the following steps of: preparing an ordered macroporous-mesoporous carbon material and TiO2 sol respectively, soaking the aged TiO2 sol on the prepared macroporous-mesoporous carbon material by an impregnation method, drying, raising the temperature and calcicining to obtain a TiO2/C composite photocatalyst material. The method for applying the titanium dioxide-carbon composite photocatalyst is that photocatalytic reaction conditions are that: the adding amount of the titanium dioxide-carbon composite photocatalyst is 1 to 6g/L; a light source is an ultraviolet or visible light source and directly irradiates a solution, the depth of the solution is 0.4 to 0.6cm, and the exposure dose per unit area on the surface of the solution is 12.5 to 12.8mW/cm<2>; and the temperature of a solution system is kept at 20 to 40 DEG C, and air is continuously introduced to maintain the concentration of dissolved oxygen. Macroporous-mesoporous carbon material supported titanium dioxide is used as a photocatalyst, so that TiO2 has high dispersity and photocatalytic activity, and is easier to recycle.