The removal efficiency and mechanism of the ultraviolet/nanoscale Fe0/H2O2 (UV/nFe0/H2O2) system for refractory organics in membrane bioreactor effluent were investigated. The most effective removal of organics was achieved at initial pH = 3.0, H2O2 dosage = 50 mM, nFe0 dosage = 1.0 g/L, and UV power = 15 W, with a reaction time of 60 min. Under these conditions, the absorbance at 254 nm, chromaticity, and total organic carbon removal efficiencies were 65.13%, 79.67%, and 61.51%, respectively, and the aromaticity, humification, molecular weight, and polymerization of organics were all significantly reduced. The surface morphology and elemental valence analysis of nano zero‐valent iron (nFe0) before and after the reaction revealed the formation of iron‐based (hydrated) oxides, such as Fe2O3, Fe3O4, FeOOH, and Fe (OH)3, on the surface of the nFe0. Refractory organics were removed by Fenton‐like reactions in the homogeneous and heterogeneous adsorption–precipitation of iron‐based colloids. At the same time, UV radiation accelerated the formation of Fe2+ on the nFe0 surface and promoted the Fe3+/Fe2+ redox cycle to a certain extent, enhancing the removal of refractory organics. The results provide a theoretical basis for the application of the UV/nFe0/H2O2 system to remove refractory organics in the effluent produced by the biological treatment of landfill leachate. Practitioner points: The UV/nFe0/H2O2 process is effective in refractory organics removal in leachate treatment.Humus in leachate was largely destroyed and mineralized by the UV/nFe0/H2O2 process.Active nFe0 material participated in the Fenton‐like process and was promoted by UV.The effects of nFe0 material and UV introduction were investigated. [ABSTRACT FROM AUTHOR]