Ultraviolet (UV) activated hydrogen peroxide (H₂O₂) and peroxymonosulfate (PMS) that produce various reactive oxygen species (ROS) were used to decompose the organic pollutants of semi-aerobic aged refuse bioreactor leachate tail water. The results showed that the degradation efficacies of organic pollutants in ultraviolet activated hydrogen peroxide (UV-H₂O₂) and ultraviolet activated peroxymonosulfate (UV-PMS) process is significantly better than those of single process. Factors including initial pH and oxidant dosage influenced the degradation efficiency greatly and increasing the concentration of oxidant favored the removal efficiency of organic pollutants in both two processes. Meanwhile, acidic ambient benefited the removal of organic pollutants, however, the removal efficiency of organic pollutants was reduced by increasing initial pH, especially in UV-H₂O₂ process. Under optimized conditions (initial pH value is 3, oxidant dosage is 0.084mol/L), 72.09% and 56.22% COD removal efficiencies were yielded by UV-H₂O₂ and UV-PMS processes, respectively. In addition, hydroxyl radical is the main ROS in UV-H₂O₂ process, while mostly hydroxyl radical and sulfate radical both work in UV-PMS process. The refractory aromatic compounds organics (i.e., humus) were degraded of leachate tail water in both two systems according to the results of ultraviolet-visible spectra and three-dimensional fluorescence spectrum. However, the transformation of humus in the two processes is quite different, and the degradation rate of humus in UV-PMS was more efficient than in that one. The study provides a valuable reference for recalcitrant organic degradation in landfill leachate by photochemical oxidation process.