Abstract: In order to explore an effective method for efficient and selective degradation of aflatoxin B₁ (AFB₁) in food, the aptamer functionalized modification of magnetic graphene oxide composite titanium dioxide (MGO/TiO₂) photocatalytic composite (MGO/TiO₂-aptamer) was synthesized by aptamer selective modification of MGO/TiO₂ photocatalyst, and the variation of the degradation effect of MGO/TiO₂-aptamer on AFB₁ at low concentrations and in mixed systems was investigated. The effects of different factors (initial concentration of aptamer, material addition, pH value and light exposure time) on the photocatalytic degradation of AFB₁ by MGO/TiO₂-aptamer were investigated. The kinetic behaviour of MGO/TiO₂-aptamer photocatalytic degradation of AFB₁ at different concentrations was simulated. The results showed that the TiO₂ and Fe₃O₄ particles were relatively uniformly attached to the surface of MGO sheets, the characteristic peaks of the aptamer's skeleton, base and CO-NH bonds were evident in the FTIR spectra, Ti and Fe elements as well as the specific N and P elements of the aptamer were found in the TEM diffraction spectra. The specific targeting degradation performance of MGO/TiO₂-aptamer on AFB₁ and the enhanced degradation effect on low concentration of AFB₁ were successfully verified. In addition, compared with the unmodified MGO/TiO₂ material, the degradation rate of MGO/TiO₂-aptamer in low concentration AFB₁ or mixed toxins was significantly improved, which verified its degradation enhancement effect and selective degradation performance for low concentration toxins. When the optimized conditions were the MGO/TiO₂-aptamer addition of 6 mg and UV-visible light irradiation for 120 min at pH 3, the degradation rate of AFB₁ could reach 98.3% and the photocatalytic degradation of AFB₁ followed the first-order kinetic Langmuir-Hinshelwood equation.