Abstract: In response to the shortcomings of high synthesis temperature and long reaction time in the high-temperature solid-phase synthesis of La₂Ce₂O₇ powder, La(NO₃)₃•6H₂O and Ce(NO₃)₃•6H₂O were used as metal ion sources, combined with ammonia water as a precipitant, and La₂Ce₂O₇ powder was synthesized by co-precipitation method.The transformation process of the precursor, phase changes and morphology of the product were analyzed by scanning electron microscopy (SEM) using synchronous thermal analyzer (TG-DSC), Fourier transform infrared spectrometer (FT-IR), X ray diffraction (XRD) and scanning electron microscopy (SEM). The UV absorption performance of the product was tested by and analyzed UV-visible spectrophotometer, and the the photocatalytic activity of the product was evaluated and analyzed through photocatalytic degradation of Rhodamine B dye experiment. The results show that La₂Ce₂O₇ powder is in the crystallization stage at 300−700 ℃, and smallerparticles or flocculent La₂Ce₂O₇ powder appear clearly. at 500 ℃. Compared with the high-temperature solid-phase method (synthesis temperature 1 400 ℃), the temperature of La₂Ce₂O₇ powder synthesized by co-precipitation method decreased by 900 ℃.The microporous structure between La₂Ce₂O₇ powder synthesized by co-precipitation method at 500 ℃ is more prominent, evenly distributed, and has a lower bandgap width. The UV absorption performance is the best, and compared with the powder synthesized by high-temperature solid-phase method, the UV absorption performance is improved by 21.7%.At the same time, the introduction of La₂O₃ into La₂Ce₂O₇ reduces the reactive oxygen species (ROS) generated by pure CeO₂, which can reduce the photodegradation of La₂Ce₂O₇ and does not further decrease with prolonged light exposure time,and the degradation rate tends to stabilize at 15%.The synthesis of La₂Ce₂O₇ powder using co-precipitation method can optimize its UV absorption performance as a sunscreen agent while reducing the synthesis temperature and reaction time.