The invention discloses a preparation method of mesoporous carbon @TiO2 core-shell spheres. The preparation method comprises the following steps: (1) dissolving ethylene glycol in acetone so as to obtain a solution A; (2) adding particle size-controllable mesoporous carbon spheres to the solution A, and performing ultrasonic uniform dispersion so as to obtain a suspension B; (3) adding tetrabutyltitanate to the suspension B, and performing ultrasonic uniform dispersion so as to obtain a suspension C; (4) transferring the suspension C to a magnetic stirring hydrothermal reaction kettle, and performing a solvothermal reaction on reactants under the condition of magnetic stirring so as to form a solvothermal product D; and (5) performing centrifugation on the solvothermal product D, and performing water washing, drying and grinding so as to obtain the mesoporous carbon @TiO2 core-shell spheres. The thickness of a mesoporous carbon @TiO2 core-shell sphere layer is regulated through changeof the ratio of the reactants so that the mesoporous carbon @TiO2 core-shell spheres with different shell thickness are prepared, the method is simple and easy, and the product has high visible lightabsorption capacity and a visible light catalysis effect.