Photocatalytic oxidation technology, as a green and environment-friendly new mercury removal technology, has broad application prospects. At present, most of the photocatalysis reactor systems use powdered catalyst, which has poor utilization of light source in the photocatalysis process, is not easy to recover, and has limited prospects for industrial application. Therefore, a new type of slot plate photocatalytic reactor was designed, which had the advantages of good light reception, wear resistance, long service life, small size. The mercury oxidation experiment was carried out with plate catalyst, and the catalyst was characterized in detail. Compared with the conventional fixed bed reactor system, the mercury oxidation efficiency of the slotted plate TiO2(VTiB) is increased from 64.8% to 86.0% under the UV light intensity of 80 mW/cm2. The mercury oxidation efficiency of the catalyst decreases with the increase of reaction temperature and increases with the increase of UV light intensity. In the plate catalytic system, the photocatalytic mercury oxidation performance of the Ce doped TiO2(Ce-VTiB) catalyst increases significantly, and the efficiency of 1.0% Ce-VTiB is the highest, reaching 92.4%. There are two main reasons. On the one hand, Ce doping can effectively reduce the band gap energy of the catalyst. Compared with VTiB catalyst, the band gap energy of 1.0% Ce-VTiB catalyst decreases by 0.68 eV, so that the absorption ability of the catalyst to ultraviolet light is enhanced. Under ultraviolet irradiation, the surface of Ce-VTiB catalyst particles is excited to generate ·OH active radicals, which oxidize Hg0 to Hg2+. On the other hand, some Ce atoms can combine with electrons to reduce the recombination of e-/h+.