Abstract: Graft copolymerization of bleached eucalyptus pulp with glycidyl methacrylate (GMA) induced by Fe2+-H2O2-thioureadioxide redox system was studied in detail. The mechanism of this initiator system was discussed primarily; the effects of reaction temperature and time, hydrogen peroxide and thioureadioxide dosages, monomer concentration and liquor ratio were characterized by the grafting rate, grafting efficiency and monomer conversion, and the chemical structure of grafted fiber was identified by FT-IR. Results showed that the addition of thioureadioxide can help to produce more radicals, which react with cellulose to obtain cellulose macromolecule radicals and thus proceed the graft copolymerization successfully. Proper increases of temperature, hydrogen peroxide dosage, proper decrease of liquor ratio and proper maintaining of thioureadioxide dosage are beneficial to the grafting rate and monomer conversion. Graft copolymerization can be proceeded successfully in a short time. Grafting efficiency could be generally maintained at 97% to 99%, and was almost not affected by any factor. Extremely insignificant amount of homopolymer was produced during the grafting process.