Abstract: The treatment effect of concentrated water from nanofiltration of bio-treated landfill leachate was investigated through UV-Fenton process, and different factors on TOC removal such as H₂O₂ dosage, ferrous salt dosage, pH, temperature and reaction time were also studied. The results showed that UV-Fenton process could effectively remove the organic pollutant components. The H₂O₂ and FeSO₄•7H₂O dosage had a significant effect on TOC removal. The removal rate increased from 53.3% to 69.8% with H₂O₂ dosage increasing from 1 665 mg/L to 13 320 mg/L, and increased from 57.4% to 71.7% with FeSO₄•7H₂O dosage increasing from 367 mg/L to 5 500 mg/L. UV-Fenton system had a buffer effect on pH variation, and removal rate had a minor change with initial pH ranging from 2.0 to 6.0. With the temperature increasing from 20 to 60 ℃, TOC removal rate decreased slowly. TOC removal rate had a sharp increase in first 30 min and increased slowly later and, after 2 h, TOC removal rate no longer increased basically.