The invention provides a preparation method of a cerium-doped zinc oxide photocatalyst. The preparation method comprises the following steps that zinc is taken as the positive pole, a noble electrodeis taken as the negative pole, an aqueous solution containing conducting salt, Ce<3+> and 2-methylimidazole is taken as a conducting solution for electrolysis, and Ce/ZIF-8 is obtained; the Ce/ZIF-8 is calcined to obtain the cerium-doped zinc oxide photocatalyst. According to cerium-doped zinc oxide photocatalyst and the preparation method thereof, the zinc is taken as the positive pole, anodic dissolution occurs under the action of a certain current, Zn<2+> enters an electrolyte to react with the 2-methylimidazole to generate ZIF-8 with a porous structure, the Ce<3+> in the solution is loadedin the porous ZIF-8 structure, and calcination is carried out to prepare a Ce/ZnO photocatalyst, and the Ce/ZnO photocatalyst is applied to the field of organic pollutants of photocatalytic degradation, has good application prospects, and has a good degradation effect on methyl orange, methylene blue and the like.