The influence of inhibitor concentration on the grafting yield was studied in different grafting system. It was found that different inhibitors had distinct effect on grafting yield in preirradiation or mutual irradiation method. In mutual irradiation method, Mohr,s salt is much weaker than bluestone in inhibiting homopolymerization with the same wt%. At high temperature, the grafting yield decreases with increasing concentration of Mohr,s salt, but increases at low temperature in some range of Mohr,s salt concentration. It can be interpreted that in the presence of Fe,2+, diperoxides and hydroperoxides may decompose at low temperature to form radicals which can initiate the grafting.