Some influencial factors of radiation induced graft of styrene-divinylbenzene onto polypropylene fibers have been studied by ,60,Co γ-rays. The results show that the self-polymerization will be less and the intake yield will be higher with monomer concentrations of 20%—25%, and the absorbed dose is higher than 15kGy. When the polypropylene fiber soaked in the graft solution for over 7h before the reaction, the influence of diffusion on the reaction can be avoided, with increased intake yield. Moreover, if the swelling is the dominant effect and the definite after-reaction time is kept, the intake yield improves. The best process of radiation induced grafting reaction was obtained by the study. The intake yield of products is 200%—280%, with a good mechanical property. It provides the eligible intermediate product for the large-scale production of ion exchange fiber.