Abstract: ZnO, La³⁺/ZnO, Ce³⁺/ZnO and La³⁺-Ce³⁺/ZnO photocatalysts were prepared by a sol-gel process and characterized by X-ray diffraction, transmission electron microscopy, ultraviolet and visible spectrophotometry, and BET specific surface area analysis. The photocatalytic activity of these photocatalysts was investigated by photodegradation of methylene blue (MB). The prepared La³⁺-Ce³⁺/ZnO photocatalyst is rectangular column shapes, with the average size of 57.3 nm. La-Ce codoping can increase the crystallinity of ZnO, promote the grain growth of ZnO, and improve the photocatalytic activity of ZnO greatly. In the photocatalytic degradation of 500 mL of 10 mg·L^-1 MB, the photocatalytic degradation rate of MB with La³⁺-Ce³⁺/ZnO as a photocatalyst is 93.7%, which is 21.4%, 19.2%, 9.3% higher than those with pure ZnO, La³⁺-ZnO, Ce³⁺-ZnO as photocatalysts, respectively.