The invention discloses a preparation method of an activated carbon fiber membrane loaded TiO2/ZnO photocatalyst. The preparation method comprises the following steps: respectively preparing a cellulose acetate solution and a precursor solution; evenly mixing the cellulose acetate solution and the precursor solution to obtain a quenching solution; carrying out thermally induced phase separation on the quenching solution at the temperature of minus 50-0 DEG C to obtain CA/TiO2/ZnAc composite fibers; and after hydrolyzing the CA/TiO2/ZnAc composite fibers in an ethanol solution of sodium hydroxide, soaking and activating the CA/TiO2/ZnAc composite fibers in an ammonium chloride solution at the temperature of 80 DEG C, and finally carbonizing the CA/TiO2/ZnAc composite fibers in a nitrogen atmosphere at the temperature of 400-500 DEG C to obtain the activated carbon fiber membrane loaded TiO2/ZnO photocatalyst. The preparation method has the beneficial effects that a thermally induced phase separation method and an activating and carbonizing method are used together, the various raw materials are easily obtained, and the preparation method is simple.