The chelating fiber containing amidoxime group has been synthesized by graft copolymerization of acryloonitrile (AN) and acrylic acid (AA) onto polypropylene (PP) and amidoximation after electro-beam (EB) preirradiation. The article systematically studies the influence factors of grafting rate. Such as preirradiation dose, reaction time and temperature and monomer concentration. Optimum grafting results could be achieved by irradiating the PP non-woven material to 200 kGy and reacting for 4 hours at 75℃ with 50% monomer concentration of AN/AA = 40/60, while adding 0.05mol/L H,2,SO,4, and Mohr’s of 0.08% in concentration.Inhibiting effect of [(NH,4,),2,Fe(SO,4,),2,] was also studied. The results of FT-IR revealed the total grafting rate which varied with the monomer concentration. The effect of the monomer ratio on the total grafting rate was associated to the stability of the monomers. For the monomer concentration range under investigation, the total grafting rate increased with the monomer concentration.